Mayor-elect Bill de Blasio was expected on Thursday morning to name William J. Bratton to lead the New York Police Department, according to two people with knowledge of Mr. de Blasio’s decision.

The move will return Mr. Bratton to the helm of the nation’s largest force at a time of historically low crime rates and a deepening rift between officers and the public.

The appointment has been highly anticipated and will most likely be among the most consequential for Mr. de Blasio, who turned discontent with the Police Department’s stop-and-frisk practices into a key part of his winning election run.

Mr. Bratton rose to international prominence after his first tenure as police commissioner in New York in the mid-1990s and had been considered a front-runner since Mr. de Blasio began mentioning his name on the campaign trail.

The selection of Mr. Bratton, a well-known and generally well-regarded figure in law enforcement, appeared to reflect the tricky spot Mr. de Blasio finds himself in as he moves to reshape the Police Department’s street tactics, while sustaining the decline in serious crime.

New York is much changed since Mr. Bratton first took the reins in 1994. Crime rates were much higher and the issue dominated mayoral politics. With his hard-charging, press-friendly style, Mr. Bratton managed to garner considerable acclaim for the drop in crime on his watch, even as crime was falling in many other big cities as well. Now, Mr. Bratton returns to a city where crime has continued to fall and where there is less acceptance of some of the most aggressive and confrontational policing tactics.

He and Mr. de Blasio will most likely be judged on whether the city can continue to be kept safe from crime and terrorism while quieting criticism over the excesses of policing, especially in minority communities.

Mr. de Blasio was expected to make his announcement at the Red Hook Community Justice Center, a local court program that deals with quality-of-life offenses through both criminal sanctions and alternative programs. The center is in a refurbished Catholic school in Red Hook, a Brooklyn neighborhood that struggled for decades with high crime rates but has seen its fortunes improve in recent years as artists and businesses have moved to the waterfront community.