Mayor Bill de Blasio on Thursday joined the calls for embattled City Councilman Andy King to resign, following a blistering report that found the Bronx politician self-dealt, mistreated his staff and retaliated against witnesses who testified against him.

“I think the speaker’s right,” de Blasio said Thursday, agreeing with Council Speaker Corey Johnson’s call late Wednesday for the two-term lawmaker to step down. “You have to cooperate with an investigation,” de Blasio added.

Hizzoner told reporters at an unrelated press conference in Manhattan that he was troubled and saddened by the situation.

“I want to first express sorrow — I’ve known him for some years and I’ve known his wife for decades,” de Blasio said. “I’m pained at some of the things I saw.”

The damning, 48-page report from the council’s Standards and Ethics Committee found King used council resources to help plan his stepdaughter’s wedding, allowed his wife to use his staff to do work for the labor union where she works, mistreated and harassed his staff and retaliated against witnesses who testified to the ethics panel about his misbehavior.

It recommends that King be suspended without pay for 30 days, lose all of his committee assignments, pay a $15,000 fine and shield his staff from future abuse by putting an independent monitor in charge of his office.

Johnson has set a Monday vote to ratify the punishment recommendations.