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.