The British decimal twenty pence coin (often shortened to 20p in writing and speech) is a denomination of sterling coinage worth 1⁄5 of a pound. Like the 50p coin, it is an equilateral curve heptagon. Its obverse has featured the profile of Queen Elizabeth II since the coin's introduction on 9 June 1982. Four different portraits of the Queen have been used; the latest design by Jody Clark was introduced in 2015. The second and current reverse (as of 2019), featuring a segment of the Royal Shield, was introduced in 2008.

As of March 2014 there were an estimated 2,765 million 20p coins in circulation, with an estimated face value of £553.025 million. Of this estimated number, between 50,000 and 200,000 of these coins are undated mule coins minted in 2008 after the dies for the old and new designs were accidentally mixed up during the minting process.

Beyond the usual commemorative versions, no 20 pence coins were minted for general circulation in 2017. This was because the concurrent introduction of the new version of the one pound coin had put enough 20 pence (and two pound) coins back into circulation, as people emptied coin jars primarily for the older one pound coin that was due to be withdrawn.

20p coins are legal tender for amounts up to the sum of £10 when offered in repayment of a debt; however, the coin's legal tender status is not normally relevant for everyday transactions.