In a photo snapped by one onlooker, Bieber is seen in an ill-fitting brown wig, mustache, sunglasses and a suit jacket and tie that he paired with an untucked button-down shirt. As for Fallon, he's sporting a longer blonde wig as well as a mustache, sunglasses and a suit jacket and tie.
In the photos shared by Instagram user Jonathan Alegre, the pair appear to be dancing, with Fallon even pulling out a pink scarf to wave around.
After the shoot, Bieber ditched his disguise and greeted fans.
The 24-year-old singer and 43-year-old host were presumably filming something for The Tonight Show though they have yet to mention anything on social media. Fallon did, however, keep his disguise on to promote Tuesday's show, which did not include Bieber.
This isn't the first time the "Sorry" singer has gone unrecognized in NYC. Back in July 2016, Pokemon Go fans were so excited about the game that they didn't realize that Bieber was playing right alongside them.