This naughty nanny never should have been near her son.

That’s the cry of an angry Upper West Side mom after a babysitter sent by a service bolted with her infant boy to New Jersey, where the crazed caretaker tried to torch an ex-boyfriend’s car.

“I’m sick to my stomach,” said angry mother Bethany Carlson, who discovered that sitter Leslie Rosario, 31, got arrested Friday for taking her one-year-old on the ill-fated attack. “I will never use a service like this again.”

The online Sittercity.com boasts of having “connected millions of families and sitters” since 2001, but Carlson said it put her child at risk.

“I’m furious that they don’t take responsibility for who’s on their site. There are so many things that could have happened. Who can trust this site? My mind goes to the Upper West Side nanny killer. It’s fresh in everyone’s minds,” she said.

Carlson, 42, and her husband, Frank Jakoubek, hired Rosario in early September to watch their son, Frankie, three to five days a week.

They paid $35 a month to the sitting site and were comforted that Rosario’s profile was “verified” and that she “had references,” Carlson said.

But she said she had a “gut feeling” about their new nanny, who showed up late for her shifts and made different excuses for not arriving on time.

New Jersey cops said Rosario took Frankie with her on Oct. 5 when she drove 30 miles to Mahwah, NJ, and set fire to the license plate of her former boyfriend’s 2010 Mercedes-Benz outside the Sheraton Hotel on Route 17, leaving the baby in the lobby.

Rosario has been charged with third-degree arson and endangering the welfare of a child.

Carlson had no idea her baby was in harm’s way or that Rosario had strayed from strict instructions not to put Frankie in a car.

Cops detained Rosario at the hotel but she gave them a fake name for Carlson, so the boy’s family had no clue what was going on.

Rosario, who avoided being arrested at that time, then failed to show up for work at Carlson’s home on Oct. 8, later claiming that she had been robbed at knife-point.

Carlson told Rosario to take the week off but fired her on Oct. 15 after the building super informed her that he previously had seen Rosario “take Frankie in her car and rush out of here.”

Rosario, who was released from Bergen County jail in Hackensack, could not be reached for comment.

Her Sittercity.com profile says she has 12 years of babysitting experience and is “fun, energetic, caring, but most of all reliable.”