The Return of the King goes down on Christmas Day this NBA season ... so how should Lakers fans treat LeBron James after he bolted for the Sixers??

If ya ask Magic Johnson, he says hold the boos -- show the four-time champion some love!!

TMZ Sports caught up with the Hall of Famer and Lakers legend outside "Jimmy Kimmel Live" on Tuesday ... and had to get his thoughts on the big matchup going down on December 25.

Magic feels like, with all James was able to accomplish for the Purple and Gold, it's only right the fanbase thanks the guy with some applause ... even though he'll be in a visitor's jersey for the nationally televised contest.

It'll be an interesting one, to say the least -- not only is he going back to his old stomping grounds, but James will also be up against his own son, Bronny, for the first time.

Despite Magic's wishes, we're sure there will be some jeers ... but it sounds like both sides were pretty cordial in the split, sharing kind words after James' departure was confirmed.