Marley Watkins' second-half goal booked Kilmarnock's place in the last eight, as they knocked out holders Celtic at Rugby Park.
Earlier in the day, Dylan Vente and Elie Youan were on the scoresheet for Hibernian, who defeated Raith Rovers 2-1.
Heart of Midlothian ran out 4-0 winners against Partick Thistle at Tynecastle, with new signing Odel Offiah marking his debut with a goal.
They join Aberdeen, Rangers, Livingston, St. Mirren & Ross County in the Quarter-Finals.
