Progress results have Campbell almost 1900 votes clear of his closest rival, Alex Crackett, with about 2600 votes left to count.
"It’s been a long election campaign and to be honest towards the end I was just wishing it was over.
"I feel very, very grateful to the people who voted for me."
Mr Campbell served a single term as a councillor after racking up the second most votes in the 2022 election and was appointed deputy mayor by Nobby Clark.
Looking ahead, he wanted to prioritise finding a solution to the city’s old Briscoes building which was burnt-out in a 2023 fire and keeping rates under control.
Selecting chair roles for the incoming council would be critical, he said.
The upcoming week would include meetings with the chief executive and all councillors.
"Councils are under enormous cost pressure, particularly around water cost. And really, it’s going to be extremely challenging to try to do what we’re required to do by the government and still keep rates low."
The result came on a special day for Mr Campbell who was celebrating his wedding anniversary with wife Jessie.
Originally from Scotland, the pair moved to New Zealand with their young family in the early 1980s and Campbell took up a job at Tiwai Point aluminium smelter.
His election website showed he spent 28 years travelling the world with Rio Tinto — a metals and mining giant — but said he always came back to Invercargill.
Mr Campbell said his interest in local politics was piqued after the mayoral forum asked him to manage the Southland Regional Development Strategy in 2015.
As for other seats at the council, both Steve Broad and Ms Crackett had secured re-election but the organisation was yet to confirm any other winners, including for the mayoralty, due to the number of votes still to count.
Progress results have all Invercargill councillors who sought re-election returning, plus the arrival of Marcus Lush, Ian Reeves and Lisa Tou McNaughton.
Results could change once votes collected on Saturday and special votes are accounted for.
Preliminary results are expected on Monday, followed by final results later this week.
LDR is local body journalism co-funded by RNZ and NZ On Air.
