He is seeking the 12th congressional seat, which is being vacated by retiring Democratic Representative Jerry Nadler, and has submitted documents to the Federal Election Commission.
Conway, previously a conservative whose ex-wife Kellyanne served as a senior aide to Donald Trump, is described by a source as a "seasoned fighter against Trump and Trumpism" considering taking his fight to Congress.
His decision to run as a Democrat underscores his significant shift away from the Republican Party, and he joins about a dozen other candidates in the crowded race for the Manhattan district.
Conway, 62, hinted at his political aspirations by departing his podcast, with the Democratic primary scheduled for June and the general election in November.