Tim Wu, the influential law professor and former candidate for lieutenant governor, is joining the office of the New York State attorney general, Eric T. Schneiderman.

Mr. Wu’s appointment brings a well-known figure in technology circles to Mr. Schneiderman’s office, which has sought to assert itself as a watchdog over technology companies and the so-called sharing economy.

Mr. Wu, who starts his job on Monday, will serve as a senior lawyer and special adviser to Mr. Schneiderman, the attorney general’s office said. He will be on sabbatical from Columbia Law School, where he is a professor.

“If I have a life mission, it is to fight bullies,” Mr. Wu, 43, said in an interview. “I like standing up for the little guy, and I think that’s what the state A.G.’s office does.”