"There was a smell of electrical fire and heavy smoke," said Stefan Johansson at the Air Rescue (Flygräddningen).
The alarm was sounded at 1.15pm on Sunday as the aircraft was passing over Kristianstad in south-eastern Sweden en route for Stockholm.
The flight was re-directed back to Malmö and was able to land some 15 minutes later.
"It all proceeded very calmly," said Anna Domanders at airports operator Swedavia to the local Sydsvenskan daily.
There were 49 passengers onboard at the time, none of whom are reported to have been injured in the incident.
It remains unclear what caused the smoke and will be the subject of an investigation.
The flight was operated by Malmö Aviation and is the third incident whereby one of the airline's aircraft have had to perform an emergency landing within the past year.
In December 2012 an aircraft developed an engine problem en route to Stockholm and was forced to return to Malmö.
In July 2012 the airline grabbed the headlines when a teary hostess caused panic after smoke filtered into the cabin on a flight from Malmö to Mallorca.