The 36-year-old decided to retire at the end of the season when he woke in an emotional state at 3am last Wednesday.
"The closer I have got to the end, it has probably become a little bit more evident that it might be this year - but I have treated it like my last year for the past six years," Walker told reporters on Monday.
"I knew it was the right time for me and the football club."
Walker will retire as Adelaide's all-time leading goalkicker - 706 from 316 games so far - and a favourite son of the club he supported as a kid in his birth-place, Broken Hill.
"I came here as a 75 kilo - that's pretty generous, being 75 kilos - blonde tips in my hair, quite a skinny kid from Broken Hill," he said of his arrival after being drafted in 2007.
"I just had no idea what I was walking in to."
And while he's set for another finals campaign in his swansong season, Walker won't need a premiership medal to feel content with his career.
"I'd love a premiership, I'd love a medal around my neck," he said.
"However ... if we can look each other in the eye at the end of whenever we finish and say that we had a crack and we had a swing at trying to win the premiership, then I'll be fully content with what we've been able to achieve."
Walker departs as a former Crows captain who was acclaimed the AFL's best skipper in 2016 and 2017, the year he played in Adelaide's losing grand final.
He was appointed captain by coach Phil Walsh in 2015 but needed convincing to accept the leadership role.
"I probably didn't believe that I could could do it," he said.
Walsh passed away in the middle of the 2015 season, his first as Crows coach, when stabbed to death by his mentally-ill son. Walker's leadership in the aftermath was widely lauded.
"Through a very challenging time, you have just probably got to focus on what you can do," he said.
"And it wasn't just me, we had some incredible leaders.
"We just gelled together and picked everyone up, and almost had to just get on with the task because we know one of Walshy's favourite sayings was 'just get the job done'.
"And if he was looking down, I reckon he would have been incredibly proud of what we're able to do through that really challenging time for (Walsh's wife) Meredith and her family."
Walker's career hit another massive bump in August 2021 when suspended for six games by the AFL for a racist comment to a teammate when watching a state league game.
"That was an incredibly difficult time for my family and I," he said.
"The biggest thing that I learnt was that words don't just hurt one person, they can hurt so many different people.
"I feel like I'm a better person for that mistake that I made. It's one thing that I wish never happened, but also I feel like I'm in a position that I'm better for it."
While coaching held some appeal, Walker's plans for next year include playing with mates in Broken Hill, and also watching the Crows.
"I can't wait to sit on the hill and have a beer and watch them light up Adelaide Oval," he said.
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