Winning Christchurch Central candidate Duncan Webb says unresolved problems following the Canterbury earthquakes have created a mood for change across the city.
The Labour politician beat incumbant National MP Nicky Wagner by 2265 votes, based on tonight's preliminary results.
Mr Webb said he had always been a Labour Party man, but his work with people after the earthquakes prompted him to stand.
The first-time candidate said he was surprised at how quickly he was thrust into the lead.
In 2014, Ms Wagner won the seat for a second time, with a majority of 2450. Until 2011, it was a safe Labour Party seat. But Ms Wagner won that time, by a slim 47 votes, before expanding her majority three years later.
Mr Webb said the city faced serious problems after the earthquakes seven years ago, including homelessness, which still needed addressing.
"The earthquake was one of reasons why I got involved, and thought something needed to change," he said.
He said a city-wide mood for change was one of the main contributors to his election night win.
"The earthquake has shown a whole range of issues and problems that need to be resolved across Christchurch."
Mr Webb said he had been expecting the result to be a knife-edge fight.
Labour also won the Christchurch East, Port Hills and Wigram seats.
Looking at the party vote nationwide, Mr Webb said he hoped for a bigger lift for Labour, but said there was still a strong mood for change.