Mahathi is a Carnatic musician and playback singer for film songs in several Indian languages.

Mahathi was born in Chennai to a family of Carnatic musicians. Her maternal great grandfather, Pazhamaneri Swaminatha Iyer, was a Carnatic vocalist and recipient of the Sangeetha Kalanidhi title. Her mother, Vasanthi Sekhar, was a flautist, while her father, Thiruvaiyaru Sekar was a Carnatic vocalist and disciple of M. Balamuralikrishna.

Mahathi moved to Kerala as a toddler, and did her schooling Hari Sri Vidya Nidhi School, Trichur and Sacred Heart Convent, Cochin. She graduated in Chennai from Meenakshi College, Kodambakkam with English literature as her main stream.

Mahathi married a surgeon in 2008; the couple have a child.