The Battersea North by-election, 1940 was a parliamentary by-election held on 17 April 1940 for the British House of Commons constituency of Battersea North in the Metropolitan Borough of Battersea. The seat had become vacant on the resignation due to ill-health of the constituency's Labour Member of Parliament (MP), William Sanders. He had held the seat since the 1929 general election, with a four-year gap after his defeat in the National landslide at the 1931 general election. He was re-elected at the 1935 election.