It is a member of the refounded Committee for a Workers' International, and the Trade Unionist and Socialist Coalition.

In the 1980s, Militant supporters Dave Nellist, Pat Wall and Terry Fields were elected to the House of Commons as Labour MPs.

In March 2009, the Socialist Party was invited to participate in No to EU – Yes to Democracy (No2EU), a left-wing alter-globalisation coalition by the RMT union leader Bob Crow, for the 2009 European Parliament elections.

[8] In 2018 and 2019, the party was involved in a dispute within the predecessor Committee for a Workers' International (1974) around the questions of socialism and identity politics.

[14] The Socialist Party did not publicly comment on her case, but Hannah Sell, who was Deputy General Secretary at the time, published a statement on behalf of the Executive Committee: "Combating violence against women: A socialist perspective on fighting women's oppression".