Queens- A Queens police officer has rocked the NYPD with an announcement that he is becoming a she – the first known transsexual cop in New York City.

“Everyone’s been very supportive, and I’m very happy about it,” said a smiling Officer June Lo, who, until earlier this week, was known as Officer John Lo.

“It’s taken courage, but I’m very pleased,” Lo told The Post on the way to work last night at the Queens Transit Task Force, wearing a white sleeveless blouse, tan cargo pants and sneakers, and hair in a ponytail.

Declining to comment further, the 31-year-old Lo said that at some point in the future, “I will make a statement” about the transition from man to woman.

Lo revealed the gender-bending decision Tuesday night during a roll call of Queens Transit Task Force cops.

When Lo’s name was called out by the sergeant, the cop asked to address the assembled officers and was granted permission.

“He said, ‘This is the way things are now. My name is June Lo. I’ve legally changed it from John to June,’ ” said a Queens transit cop familiar with the situation.

Lo also told the other cops that she had been taking female hormones in preparation for undergoing surgery to completely become a woman.

The hormones have enabled the slight, 5-foot-4 Asian-American officer to noticeably grow breasts over the past several months. In addition to that change, officers have seen the freckle-faced Lo grow fingernails and hair long, and wear earrings in both ears.

“He’s been like this for a while,” the Queens cop said. “He’s been transforming into a woman for a long time.”

“You don’t know, in street clothes, if he’s a male or a woman,” said the cop.

Lo told the other officers at roll call that if they had any questions about the process, they could either ask then or later privately.

The cops, most of whom were aware that Lo was in the process of becoming a female, burst into applause at the announcement by eight-year veteran.

“Some guys asked, ‘Can we still call you J.Lo?’ He said, ‘Yeah,’ ” said one cop, noting that Lo had affectionately has been known by that nickname for some time.

Lo was “totally open and not . . . scared or whatever” during the announcement, the cop said.

Helping Lo was the fact that “everyone seems to like him,” the cop said.

Officials said Lo is the first known person ever to undergo gender reassignment in NYPD history.

“His captain had no idea that this was going down at a roll call. He had J.Lo in his office for about an hour,” the cop said.

The cop said that superiors are being accommodating by allowing Lo to change in a separate room.

“He’s got a private locker room, basically,” the cop said.