The Rejoin EU Party (also known simply as Rejoin EU) is a pro-European minor political party in the United Kingdom, advocating for the country's re-entry into the European Union following its withdrawal, commonly known as Brexit. It was launched in February 2020. Richard Morley is the current leader and Richard Hewison is the current treasurer.

The party has one elected representative. Party chairman Andrew Smith was elected to the parish council in Goring-on-Thames, South Oxfordshire, in 2022.

Richard Hewison was the party's candidate in the 2021 London mayoral election, and was endorsed by Volt UK. He came eighth out of twenty candidates, with 1.1% of the vote.

The party stood candidates in the Chesham and Amersham, Batley and Spen and North Shropshire by-elections, each time receiving less than 0.5% of the votes. Hewison stood for the party in the 2021 Old Bexley and Sidcup by-election and received 0.7% of the vote.

In July 2022, the party's chairman Andy Smith won a seat on Goring-on-Thames Parish Council, marking the party's first electoral success.

In November 2022, Hewison stood as the party's candidate in the City of Chester by-election, winning 1.0% of the vote. In December 2022, Jim Newell stood for Rejoin EU in the 2022 Stretford and Urmston by-election and won 1.3% of the vote.

In July 2023, Hewison stood as a candidate in the Uxbridge and South Ruislip by-election, receiving 0.3% of the vote.

In the 2024 London Assembly election, the Rejoin EU Party increased its vote share on the London-wide list to 2.5%, up from 1.9% in 2021.