Mahesh copied Abhishek Bachchan's style of announcing his fatherhood, to break the news on his Twitter page.
"ITS A GIRL!!!!!!!!!!!!!!!!!! @DuttaLara. I Love u...," Mahesh tweeted a la Abhishek, who was blessed with a little angel in November last year.
The mother and child are healthy and fine, said a source close to the actress.
The 33-year-old former beauty queen married Mahesh in February last year. In August 2011, Lara confirmed she is pregnant with their first child.
Before going into labour, she made her last public appearance at a party Monday organised in honour of international talk show queen Oprah Winfrey at Parmeshwar Godrej's residence here.
An excited Lara, after meeting Winfrey and her favourite co-star Shah Rukh Khan Monday night, had then tweeted: "@Oprah and @iamsrk, two people I absolutely adore! Thank you for making my day! Now can go into labour happily!"