Walker was offered a one-game ban for pushing Geelong's Connor O'Sullivan into Adelaide captain Jordan Dawson in a marking contest in the Crows' one-point win last Thursday night.
The former captain's action was deemed careless conduct, with medium impact and high contact, by match review officer Michael Christian.
Adelaide's all-time leading goalkicker challenged the suspension at a tribunal hearing on Monday night.
Walker didn't speak at the hearing but, through his counsel Andrew Culshaw, argued the charge should not have been graded as high contact.
"What happened here was an attempt to put body on Connor O'Sullivan to keep him away ... to allow Jordan Dawson to mark," Culshaw told the tribunal.
"It went wrong.
"What was supposed to be a nudge to guide him away from the contest ... actually turned into a push in towards the contest.
"Walker accepts that he breached his duty of care ... he regrets that.
"There was no contact that was high. But if you're against us on that, it was of such a minor nature that, in and of itself, it doesn't rise as high or medium impact."
AFL counsel Amara Hughes said the gradings of high contact and medium impact were appropriate.
"Our case is that there is high contact, there is actual contact made to the head and neck and the top of the shoulders," she said.
"And also, that contact itself was forceful."
After hearing 35 minutes of evidence, tribunal chairman Jeff Gleeson KC and panel members Jordan Bannister and Paul Williams deliberated for 17 Â minutes before returning a verdict.
"We are comfortably satisfied that there was contact to O'Sullivan's head," Gleeson said.
"We are also comfortably satisfied the impact was appropriately graded as medium."
Walker will miss Adelaide's away game against the Western Bulldogs on Thursday night.
8°C