As he approaches his final days as top cop of the biggest force in the county, outgoing New York City police commissioner Dermot Shea has some advice for his successor: "Trust your gut."

Take care of our city. Take care of our police department.

— NYPD Commissioner Dermot Shea

Mayor-elect Eric Adams announced Wednesday morning his decision to tap Keechant Sewell, chief of detectives for nearby Long Island’s Nassau County Police Department, to be next New York Police Department Commissioner. Speaking to Fox News Digital at NYPD Headquarters just hours before Sewell’s appointment was leaked to the press, Shea said he did not yet know who his successor would be but had some words of advice for the then-unnamed next-in-line. 

NYC MAYOR-ELECT ERIC ADAMS SELECTS KEECHANT SEWELL AS THE FIRST WOMAN TO BE POLICE COMMISSIONER

"It's going to be incredibly challenging, and it's going to be so rewarding at the same time," he said. "Trust your gut. Do the right thing." 

NYPD officers wear masks in Times Square. 

NYPD officers wear masks in Times Square.  (Roy Rochlin/Getty Images)

He added: "Take care of our city. Take care of our police department."

Shea, a 30-year veteran of the force, will serve his last day with the NYPD on Dec. 31, 2021. His departure will make way for Sewell to get started come the first of the year. 

Speaking during a press conference at Queensbridge Houses in Long Island City, Queens, where she spent her childhood, Sewell addressed "all the little girls within the sound of my voice," telling them: "There is nothing you can’t do and no one you can’t become."

"It is said the NYPD is the best of the best," she later added. "We’re about to get even better."

Adams, who will be sworn in as the Big Apple’s 110th mayor on Jan. 1, 2022, lauded Sewell as exuding "what it means to be emotionally intelligent, calm, collected, competent." He called her "the woman for the job." 

"I am so proud of what she has done and what she is going to accomplish," Adams said. 

Incoming New York City Mayor Eric Adams speaks during a ceremony announcing Nassau County Chief of Detectives Keechant Sewell as the first ever female NYPD Commissioner, in Queensbridge Houses, Queens, New York City, U.S., December 15, 2021. (REUTERS/Andrew Kelly)

Incoming New York City Mayor Eric Adams speaks during a ceremony announcing Nassau County Chief of Detectives Keechant Sewell as the first ever female NYPD Commissioner, in Queensbridge Houses, Queens, New York City, U.S., December 15, 2021. (REUTERS/Andrew Kelly) (REUTERS/Andrew Kelly)

Sewell will be the first woman who hold the NYPD’s highest-ranking position in the history of the department. She was picked for the role from a pool of several other top female police officials from across the country, including former Seattle Police Chief Carmen Best.

"She carried with her throughout her career a sledgehammer, and she crushed every glass ceiling that was put in her way," Adams continued. "Today, she has crashed and destroyed the final one we need in New York City."

Fox News’ Zoe Diskin contributed to this report.