Police Commissioner Keechant Sewell disciplined the NYPD’s highest-ranking uniformed officer after he was found to have abused his authority in a 2021 gun case — and he’s now gearing up to fight the charges, The Post has learned.

NYPD Chief of Department Jeff Maddrey was served Tuesday with an official reprimand — docking him between six to 10 vacation days — for his role in voiding the arrest of a retired cop who was accused of flashing a gun at three children in Brooklyn in November 2021, according to internal affairs sources.

But Maddrey has indicated he’ll fight the punishment, according to the sources — setting the stage for him to square off against the police’s civilian watchdog, which substantiated the abuse allegations against him in April.

The Civilian Complaint Review Board had recommended that Sewell hit Maddrey with a “command B discipline” over the controversial incident.

Maddrey will now take the matter to trial inside One Police Plaza, with the CCRB prosecuting the case. The police watchdog’s online database of charges showed the discipline was pending trial Wednesday.

A spokeswoman for the CCRB confirmed the agency would handle the case, but had no information about why the charges were heading to trial or how many days the commissioner had decided to dock the chief.

The CCRB, in its investigation, found that Maddrey had abused his authority by cutting loose ex-NYPD Officer Krythoff Forrester after Forrester was arrested on allegations he pulled a gun on three kids — ages 12, 13 and 14 — who smashed a camera outside his family’s realty office in Brownsville. The youngsters said it was an accident.

Maddrey, who knew Forrester from his time as the 73 Precinct commander, overruled the arresting sergeant on Nov. 25, 2021, personally showing up at the stationhouse late that night and ordering that the charges against the ex-cop be voided.

Maddrey, who was chief of community affairs at the time, also suggested the three kids involved be arrested instead, according to the CCRB’s report.

The Brooklyn District Attorney’s Office reviewed the incident and decided the actions were not criminal. 

An attorney for the three boys has called on Maddrey to resign.

Mayor Eric Adams has defended the officer, saying he was “proud” that Maddrey was his chief of the department.

The NYPD did not immediately respond to a request for comment Wednesday.

Maddrey and his attorney did not return calls.