[7] At the 2017 United Kingdom general election Finucane contested the Belfast North parliamentary constituency for Sinn Féin; the sitting MP was Nigel Dodds of the Democratic Unionist Party.

Finucane secured Sinn Féin's highest vote share ever in the constituency but failed to unseat Dodds.

Also on the ballot were his former St Malachy's College classmates Mal O'Hara of the Green Party and Carl Whyte of the SDLP.

[11][12] Shortly after being elected Lord Mayor at Belfast City Hall, he was informed by the Police Service of Northern Ireland that loyalists had made credible threats to his life and planned to attack his family home.

[13] At the 2019 United Kingdom general election Finucane again contested Belfast North, winning the seat with 23,078 votes to Dodds's 21,135.