The 66 officers, from District B2 in Roxbury, each paid $50 to enter the contest and shaved their pre-existing facial hair to level the playing field for the contest, which ends after the officers march in the St. Patrick's Day Parade, the Boston Herald reported Monday.
The money raised by the event will go toward sending Boston children to Camp Harborview in the summer.
Deputy Superintendent Randy Halstead said he shaved for the contest after wearing his mustache for four decades.
"I just hope it doesn't come in gray now like the hair on my head," Halstead said.
The officers said winners will be picked for three categories; celebrity look-alikes, creepiest facial hair and "rock star."