A man swiped an SUV in Brooklyn on Monday — with a 6-year-old boy still sitting in the back seat, authorities said.

The child was inside the 2007 Acura MDX when his uncle, 28, left the engine running as he popped into Bernardo’s Plumbing in Canarsie around 1 p.m., according to police.

The white SUV with Georgia plates was then grabbed by a car thief from outside the shop at 9612 Avenue L, police said.

The suspect ended up ditching the car — and kid — a little under two miles away, at Georgia Avenue and Linden Boulevard, cops said.

The child was unhurt. The suspect is still at large.