The elderly woman had just left a restaurant on Patrick St when the mugger struck, knocking her to the ground and grabbing her handbag.
Her screams were heard by a man who was out celebrating his 24th birthday and hails from Glanmire, Co Cork.
He gave chase, shouting to people the man running ahead of him had taken a woman’s handbag.
The woman, it is believed, had about €180 and a mobile phone in her handbag.
Calls for help to stop the mugger were ignored and the chase along Cork’s streets lasted for more than 15 minutes.
The mugging occurred at the corner of Patrick St and Winthrop St at 9.50pm on Wednesday.
The mugger then headed down a side street by Penny’s into Oliver Plunkett St with the runner in hot pursuit.
He continued to tail him along South Mall, into Fr Matthew St and the mugger did “a couple of laps around Morrison’s Island” before he ran out of steam.
He then tried to throw some items that were in the handbag into the river, but they were retrieved by the runner. By this time the gardaí had arrived at the scene and arrested the mugger, who was also in his 20s.
The Glanmire man said he didn’t want to be named and did what any other decent person would have done under the circumstances.
However a friend said: “He didn’t hesitate and he was in training for the Cork City Marathon so he was always going to keep up with the man who stole the handbag.”
Superintendent Barry McPolin, who is in charge of policing in the city centre, said: “The young man who assisted in this incident should be commended for his civic spirit. It was obvious that he was extremely fit because he was able to keep running for so long.”
He said it was fortunate the elderly woman wasn’t injured. “But the victim was shaken by the ordeal and we are supporting her. Thankfully most of her property was recovered.”
The accused, in his early 20s, is due to appear in court.