He leaves the club third from bottom of the Vanarama National League after seven successive defeats.
The former Bournemouth midfielder had been in charge since September 2020 and guided the club to an 18th place finish last season.
But last Saturday's narrow defeat to Southend United proved to be the final straw - a result that left the Terras four points adrift of safety.
A brief statement on the club's website reads: "Weymouth Football Club this morning, can confirm, following a meeting of the board, that 1st Team Manager Brian Stock and the club have parted company."
Photo Credit: Mark Probin