Gianni Bruno's early goal proved the difference as Bastia continued their formidable run at home to move above Rennes in the Ligue 1 table.
Bruno magnificently volleyed home in the eighth minute to give Bastia a 1-0 victory at the Stade Armand Cesari for the third successive occasion as they moved up to 10th in the standings.
Frederic Hantz's men have dropped just two points at home in six fixtures and they handed Rennes a first defeat in five encounters.
The decisive moment came early on as Bruno latched on to Ryad Boudebouz's long ball from his own half, before controlling and volleying past helpless Rennes goalkeeper Benoit Costil.
Milos Krasic nearly doubled Bastia's lead immediately after but struck narrowly over, having been released inside the penalty area by Wahbi Khazri.
Rennes slowly grew into the game and home goalkeeper Mickael Landreau was forced to save well from Foued Kadir's strike on the right.
Landreau was once again alert to turn away Romain Alessandrini's strike from the edge of the area, following good work from the midfielder and Kadir.
Yet chances were few and far between before the break although Bastia nearly increased their advantage following the re-start.
Boudebouz's corner from the right was powerfully headed at goal by former Arsenal defender Sebastien Squillaci, only for Costil to somehow keep the ball out via a superb reflex save.
Costil was once again called upon to keep the deficit down to a solitary goal when his defence carelessly gave the ball away on the edge of their own box to Khazri, whose first-time strike was kept out by the Rennes goalkeeper.
Bastia continued to pour forward as Boudebouz fed Krasic down the right and the on-loan Fenerbahce midfielder whistled into the box before drawing another save from Costil.
Rennes failed to create anything meaningful in the second half although Adrien Hunou's thunderous 30-yard effort did keep Landreau on his toes.
It was Bastia who ended the stronger although they could not kill the game off as Costil saved well from substitute Claudiu Keseru.