The store was cleared of shoppers and staff at around 10am.
A spokesman for West Midlands Fire Service said: "At 10.03am today we were called to Sainsbury's, Raglan Street, Chapel Ash, which had been evacuated because of a leak from refrigeration unit.
"A fire engine and brigade response vehicle, crewed by a total of eight firefighters, responded from Fallings Park fire station.
"They inspected the unit and remained on scene as a precaution while an engineer was called and arrived to work on it.
A spokeswoman for Sainsbury's said: “Our St Marks store was temporarily closed for a brief time earlier today following an incident. We’re sorry for any inconvenience this may have caused and are now open as usual.”