Sam Springsteen, 25, was joined by his famous parents Bruce and Patti Scialfa at City Hall on Tuesday 14 January.
Bruce Springsteen, who sat with his wife in the front row, told reporters: “We’re very proud. We’re just excited for him today.”
Officials said this was the fire department’s 10th class since Mayor Steven Fulop, who was also present, took office.
More than 200 firefighters have been hired since 2013, and the department now has 666 members.
Springsteen released his latest album, the critically acclaimed Western Stars, last year.