Tanmay Agarwal of Hyderabad scored an unbeaten 323 runs off just 160 balls in a Ranji Trophy Plate Group game against Arunachal Pradesh.
Agarwal's triple century came in just 147 balls, making it the fastest in the history of first-class cricket.
He surpassed Marco Marais's record of the fastest triple century achieved in 191 balls.
Agarwal also broke Virender Sehwag's previous record for the highest runs scored by an Indian in a single day of first-class cricket, surpassing Sehwag's 284 runs.
His innings included a remarkable 21 sixes and 33 fours.
Agarwal's partnership with Hyderabad captain Rahul Singh yielded a monumental 449 runs in just 40.2 overs.