The 21-year-old has been struggling with an ankle problem and after meeting up with the England party to assess the problem it was decided that he should not travel to Switzerland for the tournament.
King, who made his full international debut against Italy in March, has missed the last four games of the season with Spurs and the injury has failed to fully recover.
The news is a blow to Under-21 boss David Platt as King was expected to be a certain starter for his side.
Blackburn Rovers ace Martin Taylor has been called into the squad as replacement for the unfortunate King.
Platt is still waiting to hear if West Ham star Michael Carrick will be able to shake off an injury to play.
