Ben Dalton was one of three people who confronted the man, who was smashing windows and damaging goods in shop windows in Manners Mall last November.
Mr Dalton confronted the offender, challenging him to drop the bar, and the other two tackled him. They were able to restrain the man until police arrived.
"This is a case in which it would have been very easy for someone to walk on by, to think 'They'll be insured' and dismiss it as someone else's problem," Mayor Prendergast said.
"But these three men decided to act. They performed a valuable service in stopping this terrifying incident, preventing further damage and ending a very real risk to public safety."
The other two men, Adam Newell and Bruce Thompson, received Safety in the City awards for their part in the incident at a ceremony in September.
Mr Dalton, who was unable to get to that ceremony, is being given his award before the Council meeting this evening.
The Mayor presents Safety in the City awards annually to people and organisations that have shown bravery and courage, dedication and passion and outstanding community spirit in safety issues.
Recipients this year included a crewman who jumped into Wellington Harbour to rescue a man who was in danger of being crushed against the wharf by his vessel, health workers on the front line in the fight against swine flu and a young mum who foiled a child abduction attempt.
The award is being made at 5.30pm at the Council Chamber, Wellington Town Hall.