John Schmidt Nielsen (born 7 April 1972) is a Danish former association football player, who played for Ikast and Viborg FF of the Danish Superliga. He moved abroad to play professionally for Southend United and Leiftur.
In summer 1996 Nielsen was signed for Southend United by player-manager Ronnie Whelan. After being allowed to join Leiftur on loan, Nielsen was handed a free transfer by Southend's subsequent manager Alvin Martin.