# List of ship launches in 1921

The list of ship launches in 1921 includes a chronological list of some ships launched in 1921.
| Date | Country | Builder | Location | Ship | Class / type | Notes |
| 5 January | United States | Bethlehem Shipbuilding Corporation | San Francisco, California | S-40 | S-class submarine | For United States Navy |
| 11 January | United Kingdom | Harland & Wolff | Belfast | Leighton | Cargo ship | For Lamport & Holt. |
| 18 January | United States | Northwest Bridge & Iron Company | Portland, Oregon | Swiftarrow | Tanker | For USSB/Swiftsure Oil Transport Co. |
| 25 January | United Kingdom | Blyth Shipbuilding & Dry Docks Co. Ltd | Blyth | Rio Azul | Cargo ship | For Thompson Steam Shipping Co. Ltd. |
| 5 February | United States | Northwest Bridge & Iron Company | Portland, Oregon | Swiftstar | Tanker | For USSB/Swiftsure Oil Transport Co. |
| 7 February | United States | Portsmouth Navy Yard | Kittery, Maine | S-11 | S-class submarine | For United States Navy |
| 10 February | United Kingdom | John I. Thornycroft & Company | Southampton | Elizabeth Stoner | Cargo ship | For J. Stoner & Co., Southampton |
| 10 February | Japan | Mitsubishi | Kobe | Submarine No. 29 (Ro-55) | Type L2 submarine | For Imperial Japanese Navy |
| 12 February | Denmark | Odense Steel Shipyard | Odense, Denmark | Leise Maersk | Cargo ship | For Maersk |
| 21 February | United States | Bethlehem Shipbuilding Corporation | San Francisco, California | S-41 | S-class submarine | For United States Navy |
| 24 February | UKGBI | Lithgows Ltd. | Port Glasgow | Doric Star | Cargo liner | For Blue Star Line. |
| 24 February | Japan | Kure Naval Arsenal | Kure | Submarine No. 34 (Ro-17) | Kaichū III-type submarine | For Imperial Japanese Navy |
| 3 March | United Kingdom | Blyth Shipbuilding & Dry Docks Co. Ltd | Blyth | Sheaf Garth | Cargo ship | For Sheaf Steam Shipping Co. Ltd. |
| 8 March | United Kingdom | William Hamilton and Company | Port Glasgow | Malia | Cargo ship | For Brocklebank Line |
| 9 March | United Kingdom | Harland & Wolff | Belfast | Windsor Castle | Passenger ship | For Union-Castle Line. |
| 10 March | United Kingdom | Harland & Wolff | Belfast | Losada | Cargo ship | For Pacific Steam Navigation Company.. |
| 10 March | Japan | Kawasaki | Kobe | Submarine No. 31 (Ro-3) | Type F2 submarine | For Imperial Japanese Navy |
| 12 March | United States | Northwest Bridge & Iron Company | Portland, Oregon | Swiftscout | Tanker | For USSB/Swiftsure Oil Transport Co. |
| 22 March | United States | New York Shipbuilding Corporation | Camden, New Jersey | Colorado | Colorado-class battleship | For United States Navy |
| 23 March | United Kingdom | I. J. Abdela & Mitchell Ltd. | Queensferry | Coniston | Coaster | For J. G. Frew & Co. |
| 25 March | United States | Pacific Coast Shipbuilding Company | Bay Point, California | Nashaba | Cargo ship | For United States Shipping Board |
| 25 March | Japan | Kure Naval Arsenal | Kure | Submarine No. 35 (Ro-18) | Kaichū III-type submarine | For Imperial Japanese Navy |
| 6 April | Germany | J. C. Tecklenborg | Geestemünde | Mark Brandenburg | Fishing trawler | For Hochseefischerei Groß Berlin |
| 9 April | United Kingdom | Swan Hunter & Wigham Richardson | Wallsend | Laconia | Ocean liner |
| 9 April | United States | Northwest Bridge & Iron Company | Portland, Oregon | Swifteagle | Tanker | For USSB/Swiftsure Oil Transport Co. |
| 14 April | United Kingdom | Harland & Wolff | Belfast | Francunion | Oil barge | For British Union Oil Co. |
| 22 April | Japan | Kure Naval Arsenal | Kure | Submarine No. 27 (Ro-16) | Kaichū III-type submarine | For Imperial Japanese Navy |
| 11 May | Japan | Mitsubishi | Kobe | Submarine No. 30 (Ro-56) | Type L2 submarine | For Imperial Japanese Navy |
| 19 May | Belgium | J Cockerill SA | Hoboken | Elisabethville | Cargo liner | For Compagnie Belge Maritime du Congo |
| 23 May | United States | Todd Drydock and Construction Company | Tacoma, Washington | Cincinnati | Omaha-class cruiser | For United States Navy |
| 24 May | United Kingdom | I. J. Abdela & Mitchell Ltd. | Queensferry | Shell-Mex 5 | Tanker | For Shell-Mex Ltd. |
| May | United States | Alabama Drydock and Shipbuilding Company | Mobile, Alabama | 3 unnamed vessels | Barges | For R. W. Hillcoat & Co. |
| 7 June | United Kingdom | Amble Shipbuilding Co. Ltd. | Amble | A. B. Gowan | Ferry | For Jarrow Corporation. |
| 9 June | United Kingdom | Harland & Wolff | Belfast | Inverurie | Tanker | For British Mexican Petroleum Company.. |
| 16 June | Norway | Naval Shipyard | Horten | Stegg | Trygg-class torpedo boat | For Royal Norwegian Navy |
| 16 June | United States | Moore Shipbuilding Company | Oakland, California | H. T. Harper | Tanker | For Standard Oil Company of California |
| 22 June | Japan | Kawasaki | Kobe | Submarine No. 32 (Ro-4) | Type F2 submarine | For Imperial Japanese Navy |
| June | United States | Los Angeles Shipbuilding and Dry Dock Company | San Pedro, California | West Greylock | Cargo ship | For United States Shipping Board |
| 2 July | United States | Moore Shipbuilding Company | Oakland, California | Tamiahua | Tanker | |
| 9 July | Finland | Sandvikens Skeppsdocka och Mekaniska Verkstad | Helsinki | Suomen Poika | Cargo ship | For Suomen Valtamerentakainen Kauppa Oy |
| 9 July | United States | Moore Shipbuilding Company | Oakland, California | Birkenhead | Tanker | For Vacuum Oil Company |
| 21 July | United Kingdom | I. J. Abdela & Mitchell Ltd. | Queensferry | Aurora | Tanker | For Eagle Oil Transport Co. Ltd. |
| 22 July | United Kingdom | Amble Shipbuilding Co. Ltd. | Amble | Anglo-Mex 101 | Tug | For Anglo-Mexican Petroleum Co. Ltd. |
| 28 July | United States | Alameda Works Shipyard | Alameda, California | F. H. Hillman | Tanker | For Standard Oil Company of California |
| 30 July | United States | Los Angeles Shipbuilding and Dry Dock Company | San Pedro, California | West Prospect | Cargo ship | For United States Shipping Board |
| 4 August | United States | Portsmouth Navy Yard | Kittery, Maine | S-12 | S-class submarine | For United States Navy |
| 5 August | United Kingdom | Harland & Wolff | Belfast | Lochkatrine | Passenger ship | For Royal Mail Line. |
| 6 August | United States | Chickasaw Shipbuilding and Car Company | Chickasaw, Alabama | Knoxville City | Cargo ship | |
| 18 August | United Kingdom | Blyth Shipbuilding & Dry Docks Co. Ltd | Blyth | Bellbro | Cargo ship | For Halifax Shipping Co. Ltd. |
| 20 August | United Kingdom | Amble Shipbuilding Co. Ltd. | Amble | A.M.P. 3 | Barge | For Anglo-Mexican Petroleum Co. Ltd. |
| 20 August | United States | Newport News Shipbuilding | Newport News, Virginia | John D. Archbold | Tanker | |
| 1 September | United Kingdom | Harland & Wolff | Belfast | Dinteldyk | Cargo ship | For Holland America Line. |
| 1 September | United Kingdom | Bartram & Sons | South Dock, Sunderland | Ramsay | Cargo ship | |
| 1 September | Germany | H. C. Stülcken Sohn | Hamburg | Rendsburg | Fishing trawler | For N. Ebeling |
| 1 September | United States | New York Shipbuilding Corporation | Camden, New Jersey | Washington | Colorado-class battleship | For United States Navy; Cancelled after signing of Washington Naval Treaty |
| 3 September | United Kingdom | I. J. Abdela & Mitchell Ltd. | Queensferry | Shell-Mex 4 | Tanker | For Shell-Mex Ltd. |
| 3 September | Finland | Sandvikens Skeppsdocka och Mekaniska Verkstad | Helsinki | Suomen Neito | Cargo ship | For Suomen Valtamerentakainen Kauppa Oy |
| 7 September | United States | Union Construction Company | Oakland, California | Mojave | Coast Guard cutter | |
| 10 September | United States | Southwestern Shipbuilding Company | San Pedro, California | La Purisima | Tanker | For Union Oil Company |
| 12 September | United States | Chickasaw Shipbuilding and Car Company | Chickasaw, Alabama | Chattanooga City | Cargo ship | |
| 14 September | United States | New York Shipbuilding Corporation | Camden, New Jersey | Empire Arrow | Tanker | For Standard Transportation Co Inc. |
| 17 September | Japan | Kawasaki | Kobe | Submarine No. 33 (Ro-5) | Type F2 submarine | For Imperial Japanese Navy |
| 19 September | United States | Los Angeles Shipbuilding and Dry Dock Company | San Pedro, California | West Chopaka | Cargo ship | For United States Shipping Board |
| 22 September | United Kingdom | Harland & Wolff | Belfast | Sophocles | Passenger ship | For Aberdeen Line. |
| 28 September | United Kingdom | Barclay Curle | Glasgow | Madura | Cargo liner | British India Steam Navigation Company |
| 29 September | United States | New York Shipbuilding Corporation | Camden, New Jersey | Richmond | Omaha-class cruiser | For United States Navy |
| 29 September | United States | New York Shipbuilding Corporation | Camden, New Jersey | Dixie Arrow | Arrow-class oil tanker | For Standard Transportation Company |
| 4 October | United Kingdom | Harland & Wolff | Belfast | Linnell | Cargo ship | For Lamport & Holt. |
| 4 October | United Kingdom | Blyth Shipbuilding & Dry Docks Co. Ltd | Blyth | Rio Blanco | Cargo ship | For Thompson Steam Shipping Co. Ltd. |
| 14 October | United Kingdom | Frederick Braby & Co. Ltd. | Deptford | Cumberland | Tank barge | For Anglo-American Oil Company Ltd. |
| 15 October | Japan | Yokosuka Naval Arsenal | Yokosuka | Submarine No. 40 (Ro-22) | Kaichū III-type submarine | For Imperial Japanese Navy |
| 17 October | United Kingdom | Amble Shipbuilding Co. Ltd. | Amble | Anglo-Mex | Tug | For Anglo-Mexican Petroleum Co. Ltd. |
| 18 October | Japan | Sasebo Naval Arsenal | Sasebo | Submarine No. 45 (Ro-26) | Kaichū IV-type submarine | For Imperial Japanese Navy |
| 20 October | United States | Portsmouth Navy Yard | Kittery, Maine | S-13 | S-class submarine | For United States Navy |
| 25 October | Japan | Yokosuka Naval Arsenal | Yokosuka | Submarine No. 41 (Ro-23) | Kaichū III-type submarine | For Imperial Japanese Navy |
| 29 October | United States | Mare Island Naval Shipyard | Vallejo, California | Decatur | Clemson-class destroyer | For United States Navy |
| 29 October | United States | Mare Island Naval Shipyard | Vallejo, California | Perry | Clemson-class destroyer | For United States Navy |
| 3 November | United Kingdom | Harland & Wolff | Belfast | Barrabool | Passenger ship | For Peninsular & Orient Steam Navigation Company. |
| 15 November | United Kingdom | Amble Shipbuilding Co. Ltd. | Amble | A.M.P. 20 | Barge | For Anglo-Mexican Petroleum Co. Ltd. |
| 17 November | United States | Newport News Shipbuilding | Newport News, Virginia | West Virginia | Colorado-class battleship | For United States Navy |
| 21 November | United Kingdom | Brown's Shipbuilding & Dry Dock Co. Ltd | Hull | Royal Firth | Coaster | For Border Shipping Co. Ltd. |
| 28 November | United Kingdom | William Denny and Brothers | Dumbarton | Hauraki | Cargo liner | For Union Steam Ship Company of New Zealand Limited |
| 29 November | Japan | Kure Naval Arsenal | Kure | Submarine No. 44 (I-51) | Kaidai I-type submarine | For Imperial Japanese Navy |
| 3 December | Japan | Mitsubishi | Kobe | Submarine No. 46 (Ro-57) | Type L3 submarine | For Imperial Japanese Navy |
| 14 December | United States | Merchant Shipbuilding Corporation | Chester, Pennsylvania | Missourian | Cargo ship | For American-Hawaiian Steamship Company |
| 15 December | United States | William Cramp & Sons | Philadelphia, Pennsylvania | Concord | Omaha-class cruiser | For United States Navy |
| December | United Kingdom | Frederick Braby & Co. Ltd. | Deptford | Northumberland | Tank barge | For Anglo-American Oil Company Ltd. |
| Unknown date | United Kingdom | Brown's Shipbuilding & Dry Dock Co. Ltd | Hull | Abington | Coaster | For Cheviot Coasters Ltd. |
| Unknown date | United Kingdom | Vickers-Armstrongs Ltd. | Barrow-in-Furness | Antonia | Refrigerated cargo liner | For Cunard Line. |
| Unknown date | Germany | Vulkan Werke. | Hamburg | Antonio Delfino | Passenger ship | For Hamburg South America Line. |
| Unknown date | Italy | Cantiere Officine Savoia | Genoa | Artena | Cargo ship | For private owner. |
| Unknown date | Germany | Hamburg-Elbe Schiffs. | Hamburg | Bianca | Cargo ship | For private owner. |
| Unknown date | Canada | Canadian Vickers Ltd | Montreal | Canadian Commander | Cargo ship | For private owner. |
| Unknown date | Canada | Harbour Marine Ltd. | Victoria | Canadian Traveller | Cargo ship | For private owner. |
| Unknown date | United Kingdom | Eltringham's Ltd | Willington on Tyne | Dalewood | Cargo ship | W France, Fenwick & Co Ltd |
| Unknown date | Italy | Stabilimento Tecnino Triestino. | Trieste | Duchessa D'Aosta | Cargo ship | For lloyd Triestino. |
| Unknown date | Germany | Nobiskrug Werft GmbH | Rendsburg | Elbe | Cargo ship | For Bugsier Reederei & Bergungs AG |
| Unknown date | Germany | Stettiner Oderwerke AG | Stettin | Günther Russ | Coaster | For Schiffart-und Assekuranz Gesellschaft GmbH |
| Unknown date | Germany | Vulkan Werft | Hamburg | Hagen | Cargo ship | For Hamburg America Line. |
| Unknown date | Germany | Stettiner Oderwerke AG | Stettin | Johannes C Russ | Coaster | For Schiffart-und Assekuranz Gesellschaft GmbH |
| Unknown date | Germany | Deutsche Werft. | Hamburg | Julius Schindler | Tanker | For private owner. |
| Unknown date | United Kingdom | Hawthorns & Co. Ltd. | Leith | London | Passenger ship | For Dundee, Perth & London Shipping Co. |
| Unknown date | Germany | Deutsche Werke | Kiel | Margarethe | Schooner | For Ernst Simon AG |
| Unknown date | Germany | Joh. C. Tecklenborg | Wesermünde | Marienfels | Cargo ship | For Hansa Line. |
| Unknown date | Germany | Deutsche Werke. | Kiel | Martha Hemsoth | Cargo ship | For private owner. |
| Unknown date | Italy | Cantiere Cerusa | Voltri | Mincio | Cargo ship | Pietro Ravano Fu Marco |
| Unknown date | Germany | Howaldtswerke | Kiel | Possehl | Cargo ship | Lübeck Line |
| Unknown date | United Kingdom | Cammell Laird & Co. Ltd. | Birkenhead | Samaria | Passenger ship | For Cunard Line. |
| Unknown date | United Kingdom | Short Brothers Ltd. | Sunderland | Sandown Castle | Cargo ship | For Union-Castle Mail Steamship Co. Ltd. |
| Unknown date | United Kingdom | Armstrong, Whitworth & Ci. | Newcastle upon Tyne | Vindeggen | Cargo ship | For private owner. |
| Unknown date | Germany | Joh. C. Tecklenborg. | Wesermünde | Wartenfels | Cargo ship | For Hansa Line. |
| Unknown date | Germany | Stettiner Oderwerke | Stettin | Wilhelm Russ | Coaster | Schiffart-und Assekuranz Gesellschaft GmbH |