Sawant, who was the general secretary of the city Congress unit had accused certain leaders from the party of misleading Maharashtra Chief Minister Prithviraj Chavan and had questioned the party's preparation during the Brihanmumbai Municipal Corporation (BMC) elections in 2012.
On joining the AAP, Sawant said that the fledgling party has strengthened the people and democracy in the country.
"I felt that issues of the common man can be resolved by joining AAP. I was upset with the functioning of the Congress, the sycophancy and people who came from outside," he told reporters during a press conference.
Another leader who has extended support to AAP is Shetkari Sanghatana's Sharad Joshi.
"We welcome the Shetkari Sanghatana's support and feel that it will bring a lot of depth to our work in rural areas. All members of the Sanghatana will campaign for AAP candidates during the Lok Sabha 2014 elections," the AAP said in a press statement issued here.