Eagles captain Luke Shuey and defender Shannon Hurn were given rousing receptions from the 47,027-strong crowd at Optus Stadium on Saturday night every time they touched the ball, while injured ruckman Nic Naitanui was feted from the sidelines.
But the emotion of the night wasn't enough to lift West Coast to victory, with Walker booting 9.4 from 19 shots on goal to help inspire the Crows to a 17.21 (123) to 12.6 (78) victory.
North Melbourne's upset win over Gold Coast earlier in the day combined with West Coast's loss to Adelaide means the Eagles finished last on the ladder for just the second time in their history.
But the silver lining to that disappointment is the fact they will now receive the No.1 pick in the national draft.
West Coast can either select Reid with that pick, or trade it on for a bounty of up to three first-round selections.
Walker's haul lifted him to 76 goals for the season and the outright Coleman medal lead, but Carlton forward Charlie Curnow (75 goals) can overtake him when he lines up against GWS on Sunday.
West Coast midfielder Tim Kelly starred against Adelaide with 35 disposals and eight clearances, while Shuey (25 disposals, five clearances) and Hurn (22 disposals) gave it their all in their final game.
Oscar Allen booted four goals.
Shuey, Hurn and Naitanui were given a guard of honour by both teams after the match.
Now that West Coast's season has finished, the attention will shift squarely towards the fate of coach Adam Simpson.
The premiership mentor is contracted until the end of 2025, and he is expected to find out early next week if the board will stick with him or sack him.
A petition to retain Simpson had attracted more than 4,900 signatures, and he received huge cheers whenever he was shown on the big screen during Saturday night's match.
Adelaide crushed West Coast by 122 points when the teams last met in round 13, with Walker cashing in with 10 goals.
Walker was the prominent figure of the opening term, booting 2.2 from six shots on goal.
His first - when he outmuscled Bailey Williams in a ruck contest and shrugged off a Jeremy McGovern tackle before snapping - was truly a thing of beauty.
His second came after taking a speccy on the back of McGovern.
But Shuey ensured Adelaide didn't have it all their own way, with the 2018 Norm Smith medallist mobbed by his teammates after booting a goal on the run off his non-preferred left boot.
The Crows were their own worst enemy in the second quarter, their shocking kicking efficiency and selfishness in front of goal costing them dearly.
Walker blew a series of golden chances, to the frustration of his teammates, as West Coast slammed through five goals to one to grab an 11-point lead at the long break.
The Crows spearhead made up for his errors with three goals in the third quarter - including two in the space of a minute.
Walker kicked goals No.6 and No.7 in the opening three minutes of the final quarter to stretch Adelaide's lead to 19 points.
And by the time Walker kicked goal No.8, the margin was 26 points and it was game over.
