The 32-year-old goalkeeper saw a three-month run in the County side brought to an abrupt halt by injury in February.
A fractured hand left him frustrated on the sidelines, but he will be ready to play a full part in pre-season training.
Derek Adams is looking forward to having the experienced shot-stopper at his disposal.
He snapped Brown up from Hibernian on a one-year deal last summer and is delighted to see an extended agreement put in place.
Adams said: "The club and Mark have agreed to extend his contract.
"Mark is recovering well from injury and will be able to start pre-season training with the rest of the squad on Thursday 27th June."