He is the second Congress MLA to switch over to TMC since the assembly polls earlier this year.
Chowdhury - who joined TMC in presence of senior party leader Abhishek Banerjee, nephew of Mamata Banerjee at its headquarters here - said Congress had lost all its credibility by forging an alliance with Left Front in the assembly polls.
"I was against this unholy and immoral alliance between Congress and CPI(M). I couldn't accept it from the bottom of my heart. But now Congress has lost all its credibility and political independence and is fast turning into a stooge of Left Front in Bengal," he said.
"I want to join TMC as I want to be part of the development process initiated by West Bengal Chief Minister Mamata Banerjee," he added.
More From This Section
Malda and Murshidabad are considered strongholds of Congress with the latter being under WBPCC president Adhir Chowdhury.
Recently in a blow to Congress and Left Front, TMC took control of Malda and Jalpaiguri zilla parishads after several of its members switched over to it. In July this year two MLAs - one each from Left Front and Congress - had switched over to TMC, pushing down the opposition strength to 74 from 76 in the 294-seat assembly.