The store detective at Boots in Newport's High Street tackled the man – who was believed to have taken two bottles of deodorant – in the street and stopped him from getting away while the police were called.
The incident happened on Thursday. Sophie Flynn, spokeswoman for West Mercia Police, said: "We were called at 12.45pm to the High Street in Newport to reports of a suspected shoplifter being detained by a member of the public. Following this, a 39-year-old from Telford was arrested on suspicion of theft and was given a caution."
Steve Lythgoe, Boots store manager, said the store detective would normally deal with an incident each day but it didn't normally end up with any suspects being wrestled to the floor.
He said: "We have a store detective in store most days and they do catch people. I would not say we are vulnerable, it is just a regular occurrence in retail stores around the country.
"It is a bit unusual, however, that someone gets wrestled to the ground because normally they go quite quickly and quietly.
"It did cause of a bit of a scene because there were quite a lot of people around and some of the schoolchildren were on lunch and the guy did not go quietly.
"We are very thankful to the store detective and to the police, they came really quickly, which they always do. They are pretty quick around here."
Patrick Beech, chairman of Newport's Chamber of Commerce, praised the store detective and said he would bring up the issue of security at the group's next meeting, which is on Monday.
He said: "I had heard about the incident. I think quite a few of the shopkeepers heard or saw something was going on and saw that there was police activity.
"I think it is very brave these days because you do not know what they might be carrying.
"What I will bring up at the next chamber of commerce meeting is that we used to have a shopwatch scheme in the town."