Geelong's only previous win this year over a current top-eight side was their two-point comeback victory against Hawthorn in round two.
But Friday night's win suggests the seventh-placed Cats, now with a 10-6 record, are not only on track to play finals but capable of doing major damage.
Midfielder-forward Steve Johnson was a key player with 22 disposals, two goals and a big hand in several others but was subbed out before three-quarter time with an apparent groin strain.
Veteran midfielders James Kelly and Joel Corey were very influential with their ball-winning in close, key forward Tom Hawkins found his kicking form with five majors, defender Harry Taylor snuck forward for two goals and youngster Mitch Duncan won plenty of the ball and kicked two majors.
The Cats, who had struggled with their starts previously this season, erased that concern by kicking 4.5 to zero in the first 20 minutes, then were always in control to put a huge query over the sixth-placed Bombers' top-four ambitions.
Geelong dominated the midfield early.
Essendon steadied to reduce the margin to 10 points midway through the second term.
But the Cats kicked the last three goals of the first half and three in the first 10 minutes of the second to stamp their ascendancy and surge 45 points clear.
The second half started with Corey effecting a desperate smother in the centre square, then scooping up the ball and sending a perfect pass onto the chest of Hawkins for a goal.
Minutes later, Essendon youngster Mark Baguley turned the ball over with a terrible short pass, allowing Paul Chapman an easy major.
When Taylor then floated forward to mark and goal from close range, the result was virtually beyond doubt.
Young ruckman Tom Bellchambers was excellent for the Bombers, dominating the hit-out count and kicking his side's only three goals of the third quarter, while captain Jobe Watson was typically hard-working and Dustin Fletcher creative in defence.
Worryingly for Essendon, key forward Stewart Crameri appeared to struggle with an upper leg muscle injury for much of the game, while Angus Monfries, who returned from a hamstring strain, was subbed out in the third term.