Sisodia was one of the key founding members of the Aam Aadmi Party (AAP). He became a member of its Political Affairs Committee. He was elected as a Member of the Legislative Assembly in the December 2013 Delhi Assembly election, when he defeated Nakul Bhardwaj, a Bharatiya Janata Party candidate, by 11,476 votes in the Patparganj constituency of East Delhi. In the February 2015 Delhi Assembly election, which resulted in a landslide victory for AAP, he was again elected from Patparganj, defeating Vinod Kumar Binny of the Bharatiya Janata Party by over 28,761 votes. In 2020 Delhi Legislative Assembly election, he again defeated Ravinder Singh Negi, a BJP candidate by over 3000 votes.
