Middlesbrough's elected mayor Ray Mallon, 58, put a man in a headlock and held on with the help of two shop assistants until police arrived.
Mr Mallon, who was on a day-trip to the Scottish capital, was outside the Laing jewellers on Frederick Street when the incident occurred.
He said: "I was visiting Edinburgh for the day and looking at some watches in the window of a jeweller's shop when I noticed a commotion inside. Suddenly a man came sprinting out.
"What happened next was instinctive, it took me back to the old days. I stepped across the man and we grabbed hold of each other and wrestled for a few seconds. I managed to get him in a headlock and we ended up on the ground.
"The two female assistants showed great courage and deserve a lot of praise. The man was shouting and trying to get away but they did a great job helping me to restrain him until police arrived and took him into custody."
Mr Mallon was a senior detective with Cleveland Police and was feted by both Labour and Tories for pioneering a zero tolerance strategy in Middlesbrough. He won the Robocop nickname for his no-nonsense approach to crime.