The 1935 Dumfriesshire by-election was a by-election held for the British House of Commons constituency of Dumfriesshire in Scotland on 12 September 1935. The by-election was won by the National Liberal Party candidate Sir Henry Fildes.
It was the last by-election of the 1931–1935 Parliament. Only six weeks later, on 25 October, Parliament was dissolved for the 1935 general election.