Rangers' spiral into financial chaos and demotion to the lower divisions left the Scottish Premiership bereft of its standout fixture and it returned with a bang at a rocking Celtic Park.
Champions Celtic dominated possession in the early stages and took the lead after 33 minutes when Dembele headed home Scott Sinclair's corner powerfully.
Dembele doubled the lead with a precise shot three minutes before halftime but Rangers hit back just before the interval, Joe Garner heading in from close range at the far post.
Sinclair restored Celtic's two-goal cushion after 61 minutes, running on to Dembele's pass before calmly guiding the ball past goalkeeper Wes Foderingham.
Rangers' hopes of a fightback ended in the 73rd minute when defender Philippe Senderos was sent off after receiving a yellow card for deliberate handball, his second caution of the game.
Dembele scored his third goal with a neat finish and Stuart Armstrong completed the rout in stoppage time.
Celtic won the last league clash between the sides 3-0 four years ago before going on to claim the first of five consecutive titles while Rangers, record 54-times Scottish champions, fought their way back to the Premiership.
(Reporting by Ed Osmond; Editing by Ian Chadband)
