City keeper David Martin was rarely troubled in the opening half hour, but escaped without a card of either colour when he handled outside the box.
Late goals from Matt Fryatt and Andy King helped free-scoring Leicester get back to winning ways at Brisbane Road.
Lloyd Dyer grabbed Leicester's opener after 11 minutes before Adam Chambers levelled matters for Orient before half time.
Despite a dominant second half, it seemed Leicester may be denied all three points with Os keeper Glenn Morris producing a string of fine saves.
However it was not to be, as with just five minutes remaining Fryatt scored from close range before King capped off a fine display to score a last-minute third.