The Melbourne star claimed his third Keith ‘Bluey’ Truscott Memorial Trophy, becoming the seventh Demon to win the gong three times or more.
The elite midfielder finished the count on 670 votes and edged out gun teammates Christian Petracca (644) and Max Gawn (542) — who finished second and third respectively.
Oliver, 24, capped off a memorable 2021 season.
He led the Demons to a fairytale premiership win in September.
The Dees ended a painstakingly long 57-year drought when they defeated the Western Bulldogs by 74 points.
Oliver — who spent a number of junior years at Echuca before crossing to the Cats — was one of Melbourne’s star performers in the classic triumph.
The hard-nut onballer enjoyed a sublime year on the field.
Oliver averaged an eye-watering 32 disposals a game, he led the competition in contested possessions and finished second in clearances.
He was rewarded for his heroics with his second All-Australian blazer, the AFLCA Champion Player of the Year award and he finished third in the Brownlow Medal behind Echuca’s Ollie Wines.
His third success in the Dees’ best-and-fairest was the cherry on top of a truly extraordinary season.
Demons’ coach Simon Goodwin said Oliver was a deserving recipient of the club’s prestigious award.
“To be awarded the best-and-fairest in a premiership-winning side is an amazing honour, and Clayton should be very proud,” he said.
“He has worked incredibly hard on his game over the past few seasons, so it’s no coincidence that he is now getting reward for his efforts. His consistency and influence on the field is second-to-none.
“Clayton continues to excite us as a coaching group, and we look forward to seeing him develop further as a player and leader of our club in the years to come.”