Lanark and Hamilton East was a county constituency of the House of Commons of the Parliament of the United Kingdom, which was first used at the 2005 general election.

Historically a safe Labour seat, in 2015 it was gained by the Scottish National Party when they won a record 56 of the 59 Scottish seats at Westminster, ending 51 years of Labour Party dominance at UK general elections in Scotland.

Two years later, at the 2017 general election, the Conservatives surged into second place, only 266 votes behind sitting MP Angela Crawley, followed by Labour in third place, just 96 votes behind the Conservative candidate, making the seat Britain's tightest three-way marginal.

Electoral Calculus described the seat as "Traditional", characterised by working class people with lower levels of income and formal education.

The other five constituencies were: Berwickshire, Roxburgh and Selkirk, Dumfries and Galloway, Dumfriesshire, Clydesdale and Tweeddale, East Kilbride, Strathaven and Lesmahagow, and Rutherglen and Hamilton West.