Ryad Boudebouz got the hosts off to a perfect start with a six-minute opener before Wahbi Khazri doubled their advantage from the penalty spot on 23 minutes.
Mathieu Coutadeur got Lorient back into the game just after the half-hour mark but when Milos Krasic scored a third for Bastia on 79 minutes, the writing was on the wall.
Ivorian midfielder Romaric added a fourth with 11 minutes remaining to add a gloss to the scoreline and ensure Bastia's unbeaten home record so far this season was maintained.
The Corsican side are now on 12 points from nine games played while Lorient, who had midfielder Larry Azouni sent off with five minutes left, remain in the bottom three with seven.
- Sports & Recreation
- Larry Azouni
- Wahbi Khazri