Wisniewski, who served in the Assembly since 1996 and once headed the state's Democratic committee, declared in an email he's "proud to announce I'm running for governor of New Jersey" and asked supporters for donations.
He's the third Democrat to declare a gubernatorial bid.
"I'm in," Wisniewski told NJ Advance Media on his way to Atlantic City for the state League of Municipality's annual conference, a traditional launching pad for statewide races.
Wisniewski's primary competition for the moment is against former banking executive Phil Murphy, whose early support of top officials and deep war chest largely cleared the field of Democrats eyeing a statewide run.