World champion Mayweather was seen leaving Miami's training facilities on the weekend, and James reveals that the meeting will inspire the team as they look to win the NBA title for the third successive year.
"With him being 17 years-and-0 - we're trying to defend two titles - he's been defending for a long time," he told reporters.
"He definitely knows where we're coming from. It's definitely exciting to have someone, one of the greatest of all time, to be in your presence.
"It's something you can talk about years from now when you look back on the history of sports. That guy was at our practice."
Miami begin the new season against the Chicago Bulls on October 29.