One Brooklyn undercover cop has taken over 150 illegal guns off the street — all by himself.

The officer has been involved in “Operation Phoenix” since last May, when police discovered a suspect selling guns in East New York, Police Commissioner Ray Kelly said yesterday.

The probe widened to include 11 other precincts.

In all, there have been 17 arrests since the start of the operation, Kelly announced at a news conference with Brooklyn District Attorney Charles Hynes.

And three more suspects are still being sought.

Many of the weapons — including eight assault rifles — were stolen from states along the East Coast, including Virginia, South Carolina, North Carolina and Pennsylvania, Kelly said.

The city’s top cop praised the brave work of the anonymous officer.

“He did a truly outstanding job,” Kelly said.