McDonald blasted the opener in the 22nd minute from a couple of metres as he ran in to meet a low cross from Paul Caddis on the right.
Celtic eased into a 2-0 lead in the second half when Gary Caldwell headed home in the 52nd minute after Italian Massimo Donati flicked on a corner by Japanese midfielder Shunsuke Nakamura.
Jan Vennegoor scored the third in the 55th minute after Kilmarnock lost possession in midfieldand Aiden McGeady burst clear to feed him on the left. The Dutch striker then rifled a rising shot into the top left from 20 metres.
Kilmarnock'sJamie Hammill guided a downward header into the net from five metres following Australian forward Danny Invincibile's cross on the hour. A minute later McDonald rammed in Celtic's fourth before being replaced by Georgis Samaras.
TheGreek forward ended a fine diagonal run from the run by sweeping a low shot around Combe into the far corner to complete the rout.
(Editing by John Mehaffey)