Jim Walden, a prominent and well-regarded lawyer who has represented causes across the political spectrum, will announce on Thursday that he is entering the New York City mayor’s race.

Mr. Walden, a former federal prosecutor, plans to focus on cleaning up city government and will propose a “zero-tolerance policy on corruption.” He is a political independent, and has not decided which party’s nomination to seek in the June primaries.

He is the sixth prominent candidate to challenge Mayor Eric Adams, a Democrat who was indicted last month on federal corruption charges. If Mr. Adams were to resign, party affiliation would not matter since a special election would be nonpartisan.

Mr. Walden said in an interview that corruption was a pressing campaign issue, though he declined to comment on the indictment and said that Mr. Adams had a right to defend himself.

“Whether it’s the Adams administration or many, many other administrations, corruption is a huge problem,” he said, adding that he would offer a detailed plan to “tackle graft in a way that no one has ever thought of before.”

Mr. Walden will occupy a distinct lane in the field: The five Democrats who have announced mayoral campaigns are all to the left of Mr. Adams, a centrist. They are also practiced politicians, and Mr. Walden has never run for office.