They fought back by kicking six unanswered goals either side of half-time, opened a 21-point lead midway through the last quarter, then survived a late comeback from the Hawks and won 13.15 (93) to 12.14 (86).
The result means Hawthorn is yet to beat Geelong since the 2008 Grand Final.
It also means the Kennett curse – said to have begun when, in the wake of the '08 decider, then-Hawks president Jeff Kennett said the Cats "lacked the mental drive" to beat his team – lives on.
Chris Scott's men looked slow and their kicking skills were terrible during the first half.
The Cats' gamble to field Trent West, who had knee surgery a month ago, and first-gamer Mark Blicavs in the ruck also looked to have backfired, as Max Bailey, Jarryd Roughead and David Hale helped Hawthorn dominate the centre clearances.
But a never-say-die performance from skipper Joel Selwood dragged Geelong back into the contest.
We have no hold over Hawks, says Scott
Selwood finished with 33 possessions, while Paul Chapman was another hero for the winners, turning back the clock with a virtuoso performance that yielded 25 touches and a goal.
Billie Smedts, Mathew Stokes, Andrew Mackie and Corey Enright were other outstanding performers for the Cats, while Tom Longeran held Hawthorn star Lance Franklin to just two goals.
Tom Hawkins, who was well held by Josh Gibson for much of the afternoon, Smedts, Duncan and James Podsiadly all kicked two goals for Geelong.