He was spotted by a patrolling police office shortly after 3am close to the Welsh Bridge premises in Frankwell.
A 19th century oil painting worth about £2,000 was also recovered by the officer.
The officer was on foot patrol duty in the town centre when he came across a smashed window in the auctioneer’s showrooms.
After searching the immediate area, he spotted a man acting suspiciously nearby who was detained.
The man had a slight cut to his hand which was treated at the Royal Shrewsbury Hospital.
A West Mercia Police spokesperson said: “The showroom window had been smashed causing about £800 damage and an oil painting stolen from the gallery’s window display.
“Fortunately, one of our officers on early morning duty in the town was in the right place at the right time to arrest the suspect.”
A 21-year-old man from South Wales is being held at Shrewsbury police station on suspicion of burglary.