The action by officers Saturday at the wake of Wenjian Liu was in contrast to the hundreds of police who turned their backs to video screens showing the mayor speaking at last week's funeral of Liu's police partner, Rafael Ramos.
They were shot in their cruiser two weeks ago; after the officers' deaths, the gunman, Ismaaiyl Brinsley killed himself.
Liu's funeral will be held Sunday.
The respect shown by officers Saturday came after Bratton told police that a "hero's funeral is about grieving, not grievance."
Some officers had faulted de Blasio for sympathizing with police protesters.
Uniformed police officers from across the country were among those lining up early for the wake of a second New York City police officer killed in an ambush shooting.
Among those attending Saturday's wake in Brooklyn were about 20 officers from the Los Angeles Police Department. Los Angeles Officer Hannu Tarjamo called the killings an "act of savagery that should be condemned by society."
Before the wake began, some officers sought refuge from a light snow and low temperatures in a church across the street from the funeral home.
The wake is from 1 p.m. to 9 p.m. at Ralph Aievoli & Sons Funeral home in Dyker Heights. The funeral is scheduled for 11 a.m. Sunday.
The White House says FBI Director James Comey will attend the service, representing the president.
Thousands attended the funeral last Saturday for Ramos.
PHOTOS: Funeral held for NYPD Officer Rafael Ramos
The funeral arrangements for Liu took some time, as he had relatives traveling from China.
The New York City Police Department announced street closures related to the viewing and funeral service for Liu. Street closures and parking restrictions are expected to cause traffic delays. The use of public transportation is highly recommended.
From 12 p.m. until 10 p.m. Saturday, 65th Street between 12th and 14th avenues will be closed and there will be no parking. Additionally, there will be no parking on 13th Avenue between 64th and 68th streets.
From 7 a.m. to 2 p.m. Sunday afternoon, 65th Street between 11th and 18th Avenues will be closed to vehicular traffic, there will be no parking, and pedestrian traffic will be limited. Additionally, there will be no parking on 13th Avenue between 64th Street and Bay Ridge.
The Associated Press contributed to this story.