Crewe had to win and hope for other results to go their way but it was not to be.
Leicester did a professional job and ended the season with a win that sees the Foxes end on 96 points. Champions at a canter.
Peterborough have joined Leicester in Championship with MK Dons, Millwall, Leeds and Scunthorpe in the play offs.
All Leicester's goals against Crewe came in a 12 minute 2nd half spell.
Bruno Berner, Lloyd Dyer and Matty Fryatt (with his 32nd of the season) scored the goals.