Goals from Eden Ben Basat and Charlison Benschop helped Brest to their first victory in four matches as Lorient's winless run stretched to six games.
Israel international Ben Basat broke the deadlock early on, converting from Benoit Lesoimier's cross.
The visitors then spurned several chances to claim a share of the spoils and they were made to pay for their profligacy when Benschop ensured the win for Brest in added-on time.
Landry Chauvin's men were looking to bounce back from consecutive defeats at Lyon and Toulouse and they started in ideal fashion tonight.
Lesoimier was freed down the left by Abdoulwhaid Sissoko and his ball into the area found Ben Basat, who fired past Fabien Audard in the 13th minute.
They were nearly pegged back but Alain Traore's goalbound volley was brilliantly saved by Brest keeper Alexis Thebaux, who was well beaten when Gregory Bourillon's header at the far post from Traore's free-kick was just inches over the bar.
Former Arsenal and Middlesbrough striker Jeremie Aliadiere then teed up Maxime Barthelme but his volley was only inches over.
Lorient continued to attack after the interval and Bourillon only just failed to get on the end of Traore's free-kick.
Paul Baysse headed inches wide in a rare Brest attack while at the other end Gilles Sunu dribbled past two defenders and took the ball round Thebaux before missing the open goal.
Ludovic Giuly went through on goal but Thebaux produced another excellent save and his efforts were rewarded when Benschop sealed a scarcely deserved victory for the hosts.
Mario Licka played Benschop through and though replays showed the Dutchman to be offside, he lobbed Audard in the second minute of injury time.