Chawla polled 24 votes as against 12 won by his BJP rival Arun Sood, an official spokesman said here.
The new mayor will take charge from Congress candidate Raj Bala Malik whose term had ended in December.
In the 36-member House, the strength of Congress is 13, including Union Minister Pawan Kumar Bansal, while SAD-BJP alliance has 11 seats, BSP 2, independent one and there are nine nominated councillors.
Chawla's term will be for one year, the spokesman said.
