The duo joined BJP in presence of Maharashtra CM Devendra Fadnavis and State BJP unit chief Raosaheb Danve at the CM's official residence Varsha in South Mumbai late last night.
Asked about reason for his leaving Congress, Hegde said the 'autocratic behaviour' of Mumbai Congress President Sanjay Nirupam was responsible for his decision.
"I tried to point out to party leadership about how Nirupam was damaging the party. However, no cognisance was taken of my plea," Hegde, who represented Vile Parle Assembly constituency said.
"I am a second generation Congressman. Nirupam has ruined the party," he said.
Congress won't get more than 25 of the total 227 seats in the BMC polls, he said.