James is in Las Vegas for his annual basketball camp, the LeBron James Skills Academy, and Riley has flown in for the meeting.
Riley, who sold James on leaving Cleveland to join Dwyane Wade and Chris Bosh in Miami four years ago, will try to keep James from leaving the Heat this summer.
In an effort to beef up a Heat roster that James said needs "to improve at every position," Riley reached agreements to sign center/forward Josh McRoberts and forward Danny Granger on Monday.
The meeting with Riley on Wednesday is believed to be the first meeting James has participated in since opting out of the final two years and $42 million of his Heat contract.
James's agent, Rich Paul, met with or spoke with officials from the Mavericks, Rockets, Suns, Cavaliers and Lakers last week, but James was not present.
The four-time MVP told The Associated Press he had "no complaints" when asked how free agency was going on Tuesday.
A person close to the situation told The Associated Press that James and Wade worked out together in Las Vegas on Tuesday morning. The person spoke on condition of anonymity because no one has publicly released James' itinerary.
Information from The Associated Press was used in this report.