Stunned shoppers watched on as the young animal charged through the automatic doors at Cummins's SuperValu in Ballinrobe, County Mayo.
The bull made its way through the shop before turning around and leaving from the front exit, reports The Daily Telegraph. Owner John Cummins said that no-one was injured in the incident and that the only damage sustained was to a fruit and vegetable stand.
"The bull ran down one aisle, and into the store area, where he had a good look around and came back out again. He then charged down another aisle, and out the front door again," he said.
"Amazingly, no one came directly in his path or it could have been very bad news. It was a happy ending to a story that could have gone very wrong."
He was probably looking for some chocolate to go with his milk.