An ex-NYPD sergeant will serve three months of weekends in jail after pleading guilty in Manhattan yesterday to perjury and three counts of official misconduct.

The plea by William Eiseman, 42, stems from testimony he gave two years ago in which he lied under oath that a defendant had admitted drugs were in his apartment.

Eiseman also admitted that he conducted unlawful searches on three occasions between 2007 and 2008, while working as a supervisor for the NYPD Impact Response Team and the Manhattan North Task Force.

The ex-cop’s lawyer insisted that his client had not committed an act of corruption, but was merely doing the right thing the wrong way.

“He never once arrested an individual who was not guilty of a crime,” claimed the lawyer, Andrew Quinn.

But Manhattan DA Cyrus Vance Jr. said Eiseman “abused his authority and lied under oath, violating the public’s trust.”