Alun Cairns, who represents the Vale of Glamorgan, wanted to pitch up in one of Barry's colourful seafront huts.
But the council refused as this would be classed as "commercial" use.
Mr Cairns said the decision was "ridiculous". But the seaside's loss is Ronald McDonald's gain - the surgery will be in the town's fast food venue.
The Conservative MP wanted his Saturday morning surgery on the seafront, but the council's rules state the huts cannot be rented by "charities, organisations, traders, schools etc. unless it is a pre-planned commercial week".
He said: "The beach huts are barely being used and I wanted to meet residents on Barry Island in a venue that was accessible whilst at the same time draw attention to the possible different uses for a beach hut."
A council spokesman said: "The booking was declined as the beach huts are normally available only for use by members of the public."
A south Wales MP is holding a community surgery in a McDonald's after being refused permission to hold it in a beach hut.