Police say the raiders, who all had their faces concealed, entered the service station's shop at 12.50am.
They then helped themselves to large quantities of cigarettes from behind the counter before leaving in a silver BMW.
Esso was open at the time but the shop assistant was not threatened or harmed.
The petrol station was closed this morning as police forensic teams gathered evidence but re-opened this afternoon.
Police are appealing for anyone who saw a silver BMW in the Braywick area to contact them by calling 101.
Top Ten Articles
Police officers can be seen at Ten Pin Bowling in Maidenhead tonight following an incident earlier today.