The Gaming Act 1845 (8 & 9 Vict. c. 109) was an act of the Parliament of the United Kingdom. The act's principal provision was to deem a wager unenforceable as a legal contract. The act received royal assent on 8 August 1845. Sections 17 and 18, though amended, remained in force until 1 September 2007.

Increasing concern as to the damaging social effects of gambling gave rise to a select committee of the House of Commons whose recommendations were implemented by the act. The policy of the act was to discourage betting.

However, following a 2001 report by Sir Alan Budd, in 2002, the UK government accepted that wagers should cease to be unenforceable as contracts, seeking to introduce a new liberalised regulatory regime in order to encourage the gambling industry.

Sections 1 to 9 and 15 and 16 and 19 to 24 and 26, and the first and second schedules, were repealed by Part I of schedule 6 to the Betting and Gaming Act 1960.

Sections 10 to 14 and the third schedule were repealed by section 1 of, and the Schedule to, the Billiards (Abolition of Restrictions) Act 1987

Section 25 was repealed by Part XIX of schedule 1 to the Statute Law (Repeals) Act 1976.

The whole act was repealed for Northern Ireland by article 187(4) of, and schedule 21 to, the Betting, Gaming, Lotteries and Amusements (Northern Ireland) Order 1985 (S.I. 1985/1204 (N.I. 11)).

The whole act was repealed in the Republic of Ireland by the Gaming and Lotteries Act 1956.