The truck is part of a city community policing effort set up in 2010 to reach out to children
Festooned in balloons and unveiled to the public yesterday, the blue-and-white van is marked with police insignia and has "Free Ice Cream" written in large blue letters underneath a serving hatch.
"If you had told me 30 years ago that the Boston Police Department would have an ice cream truck as part of its patrol force... I would've said you were crazy," said city police commissioner William Evans.
The truck is part of a city community policing effort set up in 2010 to reach out to children. The initiative has already handed out more than 120,000 free pots of chocolate and vanilla ice cream.
A police spokeswoman told AFP that the truck had been donated by the Boston Police Foundation and was valued at $89,000.
Although it will not make daily patrols it will be out in force at community events or on particularly hot days in the city, she said.
"I absolutely love the new truck," Evans said. "The goodwill it generates between my officers and our city's young people is undeniable and nothing short of remarkable."
Police said the ice cream is donated by a local Massachusetts dairy.