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. It covered parts of the former Clydesdale, Hamilton North and Bellshill and Hamilton South constituencies, and it elected one Member of Parliament (MP) by the first past the post voting system.

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. The result also made it the tightest three-way marginal since 1945.

Further to the completion of the 2023 Periodic Review of Westminster constituencies, the seat was abolished. Subject to major boundary changes - gaining western areas of Hamilton and losing the towns of Bothwell, Uddingston and Carluke - to be reformed as Hamilton and Clyde Valley, and was first contested at the 2024 general election.

The seat covered most of Hamilton and the rural area around Lanark. Electoral Calculus described the seat as "Traditional", characterised by working class people with lower levels of income and formal education.