Six members of the United States House of Representatives were elected in special elections in 1963.
|- ! | Clem Miller | | Democratic | 1958 | | Incumbent member-elect died October 7, 1962, but was posthumously re-elected.<br/>New member elected January 22, 1963.<br/>Republican gain. | nowrap |
|- ! | Clyde Doyle | | Democratic | 1944<br/>1946 <br/>1948 | | Incumbent died March 14, 1963.<br/>New member elected June 11, 1963.<br/>Republican gain. | nowrap |
|- ! | Francis E. Walter | | Democratic | 1932 | | Incumbent died May 31, 1963.<br/>New member elected July 30, 1963.<br/>Democratic hold. | nowrap |
|- ! | Hjalmar Nygaard | | Republican | 1960 | | Incumbent died July 18, 1963.<br/>New member elected October 22, 1963.<br/>Republican hold. | nowrap |
|- ! | Leon H. Gavin | | Republican | 1942 | | Incumbent died September 15, 1963.<br/>New member elected November 5, 1963.<br/>Republican hold. | nowrap |
|- ! | Homer Thornberry | | Democratic | 1948 | | Incumbent resigned December 20, 1963, to become a U.S. District Court judge.<br/>New member elected December 21, 1963.<br/>Democratic hold. | nowrap |