Laura Kwan received a Safety in the City certificate and citation in a brief ceremony before the Wellington City Council meeting in the Council Chamber on Wednesday evening.
The man she saved, bus driver Wallace Rameka, was present for the ceremony and made a moving speech in which he thanked Laura and the surgical and medical team which treated him.
Wallace - dressed as a Mexican, with sombrero and drawn-on moustache - was on the walkway approaching Westpac Stadium for day two of the Sevens on Saturday 6 February when he suffered a massive heart attack.
Laura, dressed as Nemo, was hurrying to see her native England play in the tournament when she saw Wallace. She performed CPR and used a defibrillator brought by stadium staff to restart Wallace's heart.
He was taken to Wellington Hospital where he underwent quadruple bypass surgery. He has made a full recovery and is shortly due to return to work for the first time since his illness.
Making the presentation, Mayor Prendergast said: "This is a wonderful story which illustrates the importance of having the right person in the right place at the right time. Even in a Nemo outfit, a cool head can save lives.
"It is also a great Wellingtonian story - anywhere else, a fish resuscitating a Mexican on a summer's afternoon might seem a little odd."
The presentation to Laura, a house officer in anaesthesia at Wellington Hospital, was due to have been made at the main Safety in the City award ceremony on 30 September. It was brought forward because Laura is shortly leaving to do voluntary work in a medical aid station in the Himalayas.
"It seems she can't help helping people," Mayor Prendergast said.