Mayor Zohran Mamdani will announce on Sunday that New York City will open a city-owned grocery store in East Harlem in Manhattan by the end of his first term, taking an early step to deliver on a key campaign pledge.

The mayor wants to spend roughly $30 million to build the store at La Marqueta, a city-owned marketplace under elevated train tracks in a predominantly Latino neighborhood. Mr. Mamdani will announce the plan at a speech on Sunday to mark his first 100 days as mayor.

As a candidate, Mr. Mamdani said he would create five city-owned grocery stores, one in each borough, in hopes of bringing down food costs for struggling New Yorkers.