The karaoke-loving ironworker — dubbed the “Second Avenue Sinatra” — who went missing nearly a month ago was found dead in an apparent suicide less than a mile from his Queens home, according to police.

Gary Russo, 54, a former Local 40 ironworker who in 2011 was helping to build the Second Avenue Subway, vanished from his Howard Beach home just after midnight on July 28.

He had been reported missing to authorities less than a week later and hadn’t been heard from since.

The Sinatra singer had been feeling blue after a recent breakup with a girlfriend, a source said.

Then about 2 p.m. Friday, officers discovered Russo’s body dangling from a rope on a tree by a near Spring Creek Park, police said.

The late hardhat gained notoriety four years ago when he belted out Frank Sinatra and Bobby Darin standards during his 30-minute lunch break at the Upper East Side construction site.

For days in the sweltering August heat, Russo would lug his Karaoke gear into work with him and perform for co-workers and passersby in front of a sign that read, “Forget all the noise, traffic and the impact of the 2nd Ave. Subway. Enjoy the music.”