The Big Apple is a popular destination on Dec. 31, with about one million people packing into Times Square every year for the countdown to midnight.
"I certainly understand that everyone's concerned and I want everyone to understand and to hear that the NYPD is ready, that the preparations for New Year's Eve are more extensive than ever," De Blasio said in a local radio interview, according to AFP.
"The planning is extraordinary. We'll have a huge number of police out on New Year's Eve, including a lot of our new anti-terror force, the Critical Response Command – that's 500-plus officers ... who are specialized in preventing terror," he added.
After the Paris attacks on Nov. 13, an ISIL propaganda video broadcast images of New York from Times Square.
Authorities hit back that there was no credible threat against the city or anywhere else in the United States, and have sought to reassure a jittery public.
"This is the best prepared city in this country to stop terrorism, and people should rest assured that they will be very well protected on New Year's Eve," De Blasio said.