Novel

• The Case of Charles Dexter Ward Written January–March 1, 1927, published May/July 1941 in Weird Tales, 35, No. 9 (May 1941), 8–40; 35, No. 10 (July 1941), 84–121

Novellas

• At the Mountains of Madness Written February–March 22, 1931, published February–April 1936 in Astounding Stories, 16, No. 6 (February 1936), 8–32; 17, No. 1 (March 1936), 125–155; 17, No. 2 (April 1936), 132–150
• The Dream-Quest of Unknown Kadath Written c. autumn 1926–January 22, 1927, first published in Beyond the Wall of Sleep, Arkham House, 1943.
• The Dreams in the Witch-House Written January–February 28, 1932, published July 1933 in Weird Tales, 22, No. 1, 86–111
• The Dunwich Horror Written summer 1928, published April 1929 in Weird Tales, 13, No. 4, 481–508
• The Horror at Red Hook Written August 1–2, 1925, published January 1927 in Weird Tales, 9, No. 1, 59–73
• The Shadow Out of Time Written November 1934–March 1935, published June 1936 in Astounding Stories, Vol. 17, No. 4, p. 110–154
• The Shadow Over Innsmouth Written November–December 3, 1931, published 1936 in The Shadow Over Innsmouth, Everett, PA: Visionary Publishing Co., 13–158
• The Shunned House Written October 16–19, 1924. Printed as a novella by The Recluse Press, 1928, but not published. First published October 1937 in Weird Tales 30, No. 4, 418–436.
• The Whisperer in Darkness Written February 24–September 26, 1930, published August 1931 in Weird Tales, Vol. 18, No. 1, 32–73

Short stories

• The Alchemist Written 1908, published November 1916 in The United Amateur, 16, No. 4, 53–57
• Azathoth Written June 1922, published 1938 in Leaves, 2, 107
• The Beast in the Cave Written April 21, 1905, published June 1918 in The Vagrant, No. 7 , 113–120
• Beyond the Wall of Sleep Written 1919, published October 1919 in Pine Cones, 1, No. 6, 2–10
• The Book Written c. 1933, published 1938 in Leaves
• The Call of Cthulhu Written summer 1926, published February 1928 in Weird Tales, Vol. 11, No. 2, p. 159–178, 287
• The Cats of Ulthar Written June 15, 1920, published November 1920 in The Tryout, 6, No. 11, 3–9
• Celephaïs Written early November 1920, published May 1922 in The Rainbow, No. 2, 10–12
• The Colour Out of Space Written March 1927, published September 1927 in Amazing Stories, Vol. 2, No. 6, 557–567
• Cool Air Written March 1926, published March 1928 in Tales of Magic and Mystery, 1, No. 4, 29–34
• Dagon Written July 1917, published November 1919 in The Vagrant, No. 11, 23–29
• The Descendant Written c. 1926, published 1938 in Leaves, 2, 107–110
• The Doom That Came to Sarnath Written December 3, 1919, published June 1920 in The Scot, No. 44, 90–98
• The Evil Clergyman Written 1937, published April 1939 in Weird Tales, 33, No. 4, 135–137
• Ex Oblivione Written 1920/1921, published March 1921 in The United Amateur, 20, No. 4, 59–60
• Facts Concerning the Late Arthur Jermyn and His Family Written 1920, published March 1921 in The Wolverine, No. 9, 3–11
• The Festival Written October 1923, published January 1925 in Weird Tales, 5, No. 1, 169–174
• From Beyond Written November 16, 1920, published June 1934 in The Fantasy Fan, 1, No. 10, 147–151, 160
• The Haunter of the Dark Written November 1935, published December 1936 in Weird Tales, Vol. 28, No. 5, p. 538–553
• The Haunted House Written 1902, unpublished, nonextant
• He Written August 11, 1925, published September 1926 in Weird Tales, 8, No. 3, 373–380
• Herbert West—Reanimator Written September 1921–mid-1922, published February–July 1922 in Home Brew, 1, No. 1 (February 1922), 19–25; 1, No. 2 (March 1922), 45–50; 1, No. 3 (April 1922), 21–26; 1, No. 4 (May 1922), 53–58; 1, No. 5 (June 1922), 45–50; 1, No. 6 (July 1922), 57–62
• History of the Necronomicon Written 1927, published 1938
• The Hound Written September 1922, published February 1924 in Weird Tales, 3, No. 2, 50–52, 78
• Hypnos Written March 1922, published May 1923 in The National Amateur, Vol. 45, No. 5, 1–3
• Ibid Written 1927/1928, published January 1938 in O-Wash-Ta-Nong, 3, No. 1
• In the Vault Written September 18, 1925, published November 1925 in The Tryout, 10, No. 6, 3–17
• John, The Detective Written 1902, unpublished, nonextant
• Life and Death Written c. 1920, unpublished, nonextant
• The Little Glass Bottle Written c.1898-9, published 1959
• The Lurking Fear Written November 1922, published January–April 1923 in Home Brew, 2, No. 6 (January 1923), 4–10; 3, No. 1 (February 1923), 18–23; 3, No. 2 (March 1923), 31–37, 44, 48; 3, No. 3 (April 1923), 35–42
• Memory Written 1919, published June 1919 in The United Co-operative, 1, No. 2, 8
• The Moon-Bog Written March 1921, published June 1926 in Weird Tales, 7, No. 6, 805–810
• The Music of Erich Zann Written December 1921, published March 1922 in The National Amateur, 44, No. 4, 38–40
• The Mysterious Ship Written 1902, Published 1959
• The Mystery of the Grave-Yard Written c.1898-9, published 1959, also known as "The Secret of the Grave"
• The Mystery of Murdon Grange Written 1918, unpublished, nonextant
• The Nameless City Written January 1921, published November 1921 in The Wolverine, No. 11, 3–15
• Nyarlathotep Written early December 1920, published November 1920 in The United Amateur, 20, No. 2, 19–21
• The Noble Eavesdropper Written 1897, unpublished, nonextant
• Old Bugs Written c. July 1919, published 1959
• The Other Gods Written August 14, 1921, published November 1933 in The Fantasy Fan, 1, No. 3, 35–38
• The Outsider Written 1921, published April 1926 in Weird Tales, 7, No. 4, 449–453
• Pickman's Model Written 1926, published October 1927 in Weird Tales, Vol. 10, No. 4, p. 505–514
• The Picture Written 1902, unpublished, nonextant
• The Picture in the House Written December 12, 1920, published July 1919 in The National Amateur, 41, No. 6, 246–249
• Polaris Written c. May 1918, published December 1920 in The Philosopher, 1, No. 1 , 3–5
• The Quest of Iranon Written February 28, 1921, published July–August 1935 in The Galleon, 1, No. 5, 12–20
• The Rats in the Walls Written August–September 1923, published March 1924 in Weird Tales, 3, No. 3, 25–31
• A Reminiscence of Dr. Samuel Johnson Written 1917, published September 1917 in United Amateur
• The Secret Cave, or John Lees Adventure Written c.1898-9, published 1959
• The Silver Key Written 1926, published January 1929 in Weird Tales, 13, No. 1, 41–49, 144
• The Statement of Randolph Carter Written December 1919, published May 1920 in The Vagrant, No. 13, 41–48
• The Strange High House in the Mist Written November 9, 1926, published October 1931 in Weird Tales, 18, No. 3, 394–400
• The Street Written c. 1920, published December 1920 in The Wolverine, No. 8, 2–12
• Sweet Ermengarde Published 1917
• The Temple Written 1920, published September 1925 in Weird Tales, 6, No. 3, 329–336, 429–431
• The Terrible Old Man Written January 28, 1920, published July 1921 in The Tryout, 7, No. 4, 10–14
• The Thing on the Doorstep Written August 21–24, 1933, published January 1937 in Weird Tales, 29, No. 1, 52–70
• The Tomb Written June 1917, published March 1922 in The Vagrant, No. 14, 50–64
• The Transition of Juan Romero Written September 16, 1919, published in Marginalia. Sauk City, WI: Arkham House, 1944, 276–284
• The Tree Written 1920, published October 1921 in The Tryout, 7, No. 7, 3–10
• The Unnamable Written September 1923, published July 1925 in Weird Tales, 6, No. 1, 78–82
• The Very Old Folk Written November 2, 1927, published summer 1940 in Scienti-Snaps, 3, No. 3
• What the Moon Brings Written June 5, 1922, published May 1923 in The National Amateur, 45, No. 5, 9
• The White Ship Written November 1919, published November 1919 in The United Amateur, 19, No. 2, 30–33

Collaborations

These collaborations range from amending a few sentences to equal partnerships to complete re-writes.

• Ashes With C.M. Eddy, Jr., first published 1924
• The Battle That Ended the Century With R.H. Barlow, written June 1934
• Bothon With Henry S. Whitehead
• The Challenge from Beyond With C. L. Moore, A. Merritt, Robert E. Howard, and Frank Belknap Long, written August 1935
• Collapsing Cosmoses With R.H. Barlow, written June 1935
• The Crawling Chaos With Winifred V. Jackson, written 1920–21, published in The United Co-operative, April 1921, Vol. 1, No. 3, p. 1–6
• The Curse of Yig With Zealia Bishop, written 1928, published November 1929 in Weird Tales, 14, No. 5, 625–36
• Deaf, Dumb, And Blind With C.M. Eddy Jr., first published 1925
• The Diary of Alonzo Typer With William Lumley, written October 1935, published February 1938 in Weird Tales, 31, No. 2, 152–66
• The Disinterment With Duane W. Rimel, written 1935, published summer 1935 in The Californian, 3, No. 1, 3–7
• The Electric Executioner With Adolphe de Castro, written c. 1929, published August 1930 in Weird Tales, 16, No. 2, 233–236
• Four O'Clock With Sonia Greene, written 1922, published 1922
• The Ghost-Eater With C.M. Eddy Jr., first published 1924
• The Green Meadow With Winifred V. Jackson, written 1918/1919, published spring 1927 in The Vagrant, 188–195
• The Hoard of The Wizarrd-Beast With R. H. Barlow
• The Horror at Martin's Beach With Sonia H. Greene, written June 1922, published November 1923 in Weird Tales, 2, No. 4, 75–76, 83
• The Horror in the Burying-Ground With Hazel Heald, written 1933–1935, published May 1937 in Weird Tales, 29, No. 5, 596–606
• The Horror in the Museum With Hazel Heald, written October 1932, published July 1933 in Weird Tales, 22, No. 1, 49–68
• In the Walls of Eryx With Kenneth Sterling, written January 1936, published October 1939 in Weird Tales, 34, No. 4, 50–68
• The Last Test With Adolphe de Castro, written 1927, published November 1928 in Weird Tales, Volume 12, No. 5, 625–56
• The Loved Dead With C.M. Eddy Jr., first published 1924
• The Man of Stone With Hazel Heald, written 1932, published October 1932 in Wonder Stories, Volume 4, No. 5, 440–45, 470
• Medusa's Coil With Zealia Bishop, written May 1930, published January 1939 in Weird Tales, 33, No. 1, 26–53
• The Mound With Zealia Bishop, written December 1929–early 1930, published November 1940 in Weird Tales, 35, No. 6, 98–120
• The Night Ocean With R.H. Barlow, written c. 1935, published winter 1936 in The Californian, 4, No. 3, 41–56
• Out of the Aeons With Hazel Heald, written 1933, published April 1935 in Weird Tales, 25, No. 4, 478–496
• Poetry and the Gods With Anna Helen Crofts, written 1920, published in The United Amateur, September 1920, Vol. 20, No. 1, 1–4
• The Slaying of the Monster With R. H. Barlow
• The Sorcery of Aphlar With Duane W. Rimel
• Through the Gates of the Silver Key With E. Hoffmann Price, written October 1932–April 1933, published July 1934 in Weird Tales, 24, No. 1, 60–85
• Till A' the Seas With R.H. Barlow, written January 1935, published summer 1935 in The Californian, 3, No. 1, 3–7
• The Trap With Henry S. Whitehead, written late 1931, published March 1932 in Strange Tales of Mystery and Terror, 2, No. 1, 73–88
• The Tree on the Hill With Duane W. Rimel, written May 1934, published September 1940 in Polaris, 4–11
• Two Black Bottles With Wilfred Blanch Talman, written July–October 1926, published August 1927 in Weird Tales, 10, No. 2, 251–58
• Under the Pyramids (also known as "Imprisoned with the Pharaohs") With Harry Houdini, written February–March 1924, published May 1924 in Weird Tales
• Winged Death With Hazel Heald, written 1933, published March 1934 in Weird Tales, 23, No. 3, 299–315

Poetry

• A Cycle of Verse
• Alfredo; A Tragedy
• An American to Mother England Published January 1916
• An Appreciation to Andrew Francis Lockhart Published 1918
• An Elegy on Franklin Chase Clark, M.D.
• An Elegy on Phillps Gamwell, Esq.
• An Epistle to the. Rt. Honble Maurice Winter Moe, Esq.
• Anthem of the Kappa Alpha Tau
• Arcadia
• Astrophobos Published c. November 25, 1917
• The Ancient Track Published March 1930
• Bells
• Bouts Rimés
• The Bride of the Sea Published c. September 30, 1915
• The Cats Published February 15, 1925
• Christmas Blessings
• Christmastide Published November 1920
• The City Published October 1919
• The Conscript
• C.S.A. 1861-1865: To the Starry Cross of the South
• Dead Passion's Flame
• Despair Published c. February 19, 1919
• De Triumpho Naturae
• Edith Miniter
• Eic Eqiyynv
• The Eidolon
• The Elder Pharos Published February 1931
• Fact and Fancy Published February 1917
• Festival
• Fungi from Yuggoth Written 1929–1930
• The Garden
• Good Saint Nick
• Hallowe'en in a Suburb Published March 1926
• H. Lovecraft's Attempted Journey betwixt Providence & Fall River on the N.Y.N.H & H.R.R
• "Homecoming," in Weird Tales (Canadian edition, second series, January 1946, vol. 38, no. 3)
• The House
• In a Sequester'd Providence Churchyard Where Poe Once Walk'd
• Lines on Gen. Robert Edward Lee Published c. May 18, 1916
• Laeta; a Lament Published February 1918
• Life's Mystery
• Little Sam Perkins
• Little Tiger
• The Messenger
• Monos: An Ode
• Nathicana Published Spring 1927
• Nemesis Published November 1, 1917
• Night-Gaunts
• The Nightmare Lake
• Oct. 17, 1919
• Ode for July Fourth, 1917 Published July 1917
• On Ambrose Bierce
• On Cheating the Post Office
• On Phillps Gamwell
• On Reading Lord Dunsany's Book of Wonder Published March 1920
• On Receiving a Picture of Swans Published c. September 14, 1915
• On the Creation of Niggers
• On The Thing in the Woods by Harper Williams
• The Outpost
• Ovid's Metamorphoses
• Pacifist War Song - 1917 Published March 1917
• The Peace Advocate
• Phaeton
• The Poe-ets Nightmare
• Poemata Minora, Volume II Published September 1902
• The Poem of Ulysses, or The Odyssey
• Poetry Fragments of HP Lovecraft
• Primavera
• Providence Written May 1924, published September 26, 1924
• Psychopompos: A Tale in Rhyme
• The Rose of England
• Revelation Published March 1919
• The Rutted Road
• The Solace of Georgian Poetry
• Sonnet on Myself
• S.S.L.: Christmas 1920
• Sunset Published May 1918
• To A Dreamer
• To Clark Ashton Smith, Esq., Upon His Phantastick Tales, Verses, Pictures, and Sculptures
• To Edward John Moreton Drax Plunkelt, Eighteenth Baron Dunsany
• Mr. Finlay, Upon His Drawing for Mr. Bloch's Tale, "The Faceless God"
• To His Mother on Thanksgiving
• Tosh Bosh
• To S. S. L.-Oct. 17, 1920
• To the Late John H. Fowler Esq.
• To Xanthippe, on Her Birthday-March 16,1925
• The Unknown
• Waste Paper
• Where Once Poe Walked
• With a Copy of Wilde's Fairy Tales
• The Wood

Essays

• A Confession of Unfaith Published February 1922
• A Descant to Avernus Written Summer 1928, published Summer 1929
• The Allowable Rhyme Published October 1915
• At the Root Written 1918
• Autobiography of Howard Phillips Lovecraft Written early 1930's, published October 1941
• The Brief Autobiography of an Inconsequential Scribbler published April 1919
• Cats and Dogs Written November 23, 1926
• Commercial Blurbs of HP Lovecraft June-July 1925, published Spring 1988
• Commonplace Book of HP Lovecraft Written early 1920-1935, published 1938
• The Crime of the Century
• The Despised Pastoral Published July 1918
• Diary of HP Lovecraft: 1925 Written 1925-6, published 2006
• Diary of HP Lovecraft: 1937 Written January-March 1937, published 1987
• In Memoriam: Henry St. Clair Whitehead Written March 1933
• In Memoriam: Robert Ervin Howard Written September 1936
• Liquor and Its Friends
• Metrical Regularity July 1915
• Notes on Hudson Valley History Written late 1930, published 2006
• Notes on Writing Weird Fiction Written in 1933, published in the June 1937 issue of the Amateur Correspondent
• Observations on Several Parts of America Written Summer 1928, published 1944
• The Renaissance of Manhood
• Sleepy Hollow To-day Written Summer 1928, published 1930
• Some Notes on a Nonentity Written November 23, 1933, published 1943
• Supernatural Horror in Literature Written late 1925–summer 1927, published 1927
• The Trip of Theobald Written Summer 1927, published September 1927
• Vermont-A First Impression Written 29 September 1927, March 1928

Letters

• Correspondence between R. H Barrow and Wilson Shepherd of Oakman, Alabama-Sept.-Nov. 1932, Written Spring 1936, published Fall 1986
• Letter to the Gallomo, December 11, 1919
• Letter to Edwin Baird, Part published in Weird Tales, Volume 2, Issue 3. October, 1923
• Letter to Clark Ashton Smith, November 27, 1927
• Letter to Farnsworth Wright, Only part published in Weird Tales, Volume 11, Issue 2. February, 1928
• Letter to J. C. Henneberger, February 2, 1924, Published January 2015
• Postcard from to Clark Ashton Smith, 14th December 1933

Legal documents

• Instructions in Case of Decrease by HP Lovecraft Written late 1936 or early 1937, published Fall 1985
• Will of H.P. Lovecraft, August 12, 1912
• Will of Annie Gamwell, January 10, 1940
• Letter from Ethel. P. Morrish & Edna W. Lewis to August Derleth & Donald Wandrei, May 2, 1941

Generally considered spurious

• The Inevitable Conflict by Paul H. Lovering Published December 1930, January 1931, in Amazing Stories This has been considered a Lovecraft pseudonym, but most writers believe this is not his work.
• The Thing in the Moonlight by J. Chapman Miske Published January 1941 in Bizarre This was published as a Lovecraft story, but it was based on a letter that he sent to Donald Wandrei.
• Satan's Servants – Copyrighted in the United States until 2045 due to (Renewal: R657862 ) by Robert Bloch Written 1935, published in Something About Cats and Other Pieces, 1949 Lovecraft provided suggestions to Bloch, but did not actually edit the story himself.