Crews from Invercargill and Kingswell attended.
A caller to emergency services shortly before 5pm reported seeing thick white smoke that "smelled weird", a Fire and Emergency New Zealand spokesman said.
Firefighters saw haze near the ceiling and people were evacuated, but by 6.15pm the air was clear and they allowed the owners of the building to return.
Employees in the building stood on the street as firefighters investigated.
One staff member, who wished to remain anonymous, said he had been told by a colleague there was smoke in the building, but did not see or smell anything.
Invercargill station officer Bradley May said Kmart staff noticed a smoke-like substance coming from a vent and, "being cautious", alerted emergency services.
The cause of the problem was unclear last night.
