The Manchester City defender was involved in a heated exchange with the Manchester United forward during the first half of the Manchester derby.
After being shoved to the ground by Walker, Hojlund confronted the England international as they squared up to each other.
The City captain then theatrically threw himself to the floor, prompting a melee involving players from both teams.
Both Walker and Hojlund were booked for their antics, but Keane was not impressed at half-time.
The Sky Sports pundit ripped into Walker as he slammed the 34-year-old's reaction.
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When asked if there should've been a red card dished out by referee Anthony Taylor, Keane responded: "Yeah, to Walker.
Keane added: "You don't mind a bit of this, this is going to happen in a game, a bit of angry bargy, of course.
"He's obviously been blocked, but Walker.. of course it's a foul and a free-kick and Hojlund's not happy and that's fine.
"But he then goes over, how can Walker [go down]? He must be embarrassed. He must be embarrassed to go down like that.
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"An experienced player, this isn't contact. Look at this! I don't know the guy and I'm embarrassed for him."
After fellow pundit and ex-Man City defender Micah Richards insisted Walker is 'better' than what the act he pulled off, an unconvinced Keane responded: "Is he? I'm not so sure.
Former Crystal Palace manager Frank de Boer also tore into Walker's behaviour.
Appearing as a pundit on Dutch TV, De Boer said: "If Kyle Walker watches that clip back, surely he can't take himself serious anymore?! It makes me furious. I find this ridicilous!
"And he even keeps laying on the ground! This is screwing up our game of football, look at how they treat each other in rugby, and then look at this."
Keane's outburst followed an X-rated pre-match rant from the former Manchester United skipper.
The ex-midfielder admitted the situation at Old Trafford 'is not great' as he swore live on TV prior to kick-off.
Walker and Hojlund's coming together was one of few standout moments in a quiet first half at the Etihad Stadium.
The opening 45 minutes also saw the hosts take the lead through Josko Gvardiol.
However, United were unable to register a single shot on goal in response to falling behind.
Gvardiol's header was his eighth league goal of 2024, more than any other Premier League defender.