"I told y'all a while back that my young King was next in line!" James wrote in an Instagram caption. "Getting better and better every night out! Tonight another example of that."
Simmons finished the game with 18 points, nine rebounds and eight assists.
Sixers big man Joel Embiid appeared to use social media to lobby James to sign with the Sixers this summer before adding, "It's not what y'all think":
James' agent, Rich Paul, also represents Simmons, which has helped the two form a relationship away from the court. They've worked out together in the offseason, and James tweeted out an All-Star vote for Simmons in January.
USA Today's Jeff Zillgitt reported in November there was a growing belief the 76ers will try to sign James when he becomes a free agent. The opportunity to team up with young stars such as Simmons and Embiid could be enticing for the four-time MVP when the time comes to get a new contract, which could be this offseason if James exercises his opt-out clause.