Production at Nilfisk fell dramatically when Germany occupied Denmark during the Second World War. During this period, Nilfisk turned its attention to producing industrial vacuum cleaners, which against all odds launched in 1940. It subsequently proved to be a major success for the company.

Nilfisk utilised its manufacturing facilities as best as it could to manufacture sidecars with stretchers for the Nimbus motorcycles used by the Civil Defence force. Oil rationing was the incentive for the production of gas generator for the Nimbus.

Both Nilfisk vacuum cleaners and Nimbus motorcycles were rationed to those with special needs for such products.

Tanned legs were produced using brown dye and a Nilfisk spray.