West Derbyshire was a county constituency represented in the House of Commons of the Parliament of the United Kingdom. From 1885, until it was replaced by the Derbyshire Dales constituency in the 2010 general election, it elected one Member of Parliament (MP) by the first past the post voting system. It was a safe Conservative seat for most of its existence.

This was the only really safe Conservative seat in Derbyshire, consisting mostly of rural villages and tourist towns like Bakewell and Matlock; Labour's only strengths were in Wirksworth and Masson, not enough to end the long-standing Conservative representation of this seat.

Historically associated with the Cavendish family, the seat and its predecessors were usually represented by one of the future Dukes of Devonshire or their relatives from 1580 until the Second World War. When the Cavendish family left the Liberals over Irish Home Rule the seat stayed loyal to them as they sat first as Liberal Unionists then as Conservatives. In 1918 the hold on the constituency was briefly broken by Charles Frederick White standing for the Liberals, but the seat was regained in 1923. In a by-election in 1944, White's son, also called Charles Frederick White resigned as the official Labour nominee in order to stand against the wartime party truce. He defeated the Conservative candidate, William Cavendish, Marquess of Hartington, and subsequently took the Labour whip in the Commons, holding the seat in the 1945 general election for Labour. The Conservatives regained the seat in the 1950 general election and have held it ever since. The closest they have come to losing was in the 1986 by-election when they held it by only 100 votes in a period of heavy unpopularity for the government of Margaret Thatcher.

• List of parliamentary constituencies in Derbyshire