It's the progressive group's first endorsement of the cycle, and comes with fundraising support and access to the PCCC's thousands-strong member base.
Sciortino has been running as the progressive in the race against five other staunch Democrats in Massachusetts' heavily Democratic fifth district.
He's also received the endorsement of Reps. Raul Grijalva (D-Ariz.), Keith Ellison (D-Mich.), Alan Grayson (D-Fla.) and Mark Takano (D-Calif.).
Last week, Sciortino held a conference call with Grayson to express opposition to military engagement in Syria, an effort PCCC cited in an email to supporters as evidence that "he is the type of bold leader we can count on."
The endorsement comes on the heels of a much-lauded television ad, Sciortino's first, that featured the candidate — who is gay — "coming out" to his Tea Party father as a progressive.
The ad received national press coverage and a positive response locally. And it overshadowed the launch of state Sen. Katherine Clark's first ad.
Sciortino remains the underdog in the race, with a little less than a month to go until the decisive primary day, but the PCCC endorsement is sure to help him raise his profile in the district.