The pair were involved in a heated clash at the Etihad Stadium on Sunday afternoon after Walker shoved Hojlund to the ground.
Both players were then booked after the City captain hit the deck following a face-to-face exchange with Hojlund.
United and Hojlund had the last laugh as they snatched all three points thanks to late goals from Bruno Fernandes and Amad Diallo.
The Man United forward has now sent Walker a cheeky message on Instagram after his side's dramatic victory.
Sharing a snap of his confrontation with Walker, Hojlund wrote: "Manchester is red. Violets are blue.
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Walker's theatrical fall to the turf was slammed by Roy Keane at half-time, with the former United skipper calling the full-back's behaviour 'embarrassing'.
Their altercation had stemmed from a foul by Walker on Hojlund, which prompted an angry reaction from the Dane.
A melee ensued between players from both teams before referee Anthony Taylor booked both Walker and Hojlund.
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Reacting at half-time, Keane fumed: "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.
"An experienced player, this isn't contact. Look at this! I don't know the guy and I'm embarrassed for him."
Hojlund went on to have the last laugh after the Red Devils' late turnaround.
The win meant United avoided losing three consecutive league matches for the first time since 2015.
However, they remain 13th in the Premier League despite securing their sixth victory of the campaign.
As for City, the champions have now won just one of their last 11 matches in all competitions.
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Pep Guardiola's side sit fifth behind Nottingham Forest and nine points adrift of leaders Liverpool.
The Spaniard will be hoping to inspire a response away to Aston Villa next Saturday, whilst United face Tottenham in the Carabao Cup on Thursday.