The Los Angeles Lakers forward, the NBA's all-time leading scorer and four-time champion, joins a list of celebrity starters who have carried out the ceremonial role over the decades.
Hollywood actor Brad Pitt was the starter in 2016 and Steve McQueen lowered the French flag to start the race in 1971, the year he starred in the movie Le Mans.
'King James' will unleash the 62-strong field at 1600 CET on Saturday.
"There’s nothing like seeing and experiencing sports at their highest level," said James.
"It’s an honor for me to be part of this historic moment in motor sport and help celebrate the Centenary of one of the biggest sporting events in the world."
James is a partner in Fenway Sports Group, who co-own the RFK Racing NASCAR team.
The US-based stock car series is celebrating its 75th anniversary and has a special entry at Le Mans driven by seven times NASCAR champion Jimmie Johnson, 2009 Formula One champion Jenson Button and former Le Mans winner Mike Rockenfeller.
