Mardenborough has been drafted in as a replacement for the injured Lucas Ordonez by RJN Motorsport, the squad with which the Englishman has been associated with since 2011.
The 27-year-old finished sixth in the 2014 British GT championship with RJN and his last Blancpain GT outing with the outfit at Silverstone in 2015 yielded a third place finish in the Pro-Am class.
He will drive RJN’s #23 Nissan GT-R GT3, sharing the car with fellow Brits and full-season drivers Alex Buncombe and Matt Parry.
“I’m very excited to do another race with Bob Neville and the RJN guys, but I wish it were under better circumstances,” Mardenborough said.
“I feel bad for Lucas. I know he is shattered. It is bad enough to miss out on a race through injury but is even worse when it is in your home country, and you miss out on the chance to race in front of your fans, family, and friends.”
Ordonez, who won the first edition of Nissan’s gamer-to-racer programme back in 2008, has been ruled out of the event after breaking his shoulder in a cycling accident.
The Spaniard consulted renowned sports injury specialist Dr. Xavier Mir, who deemed him unfit for his home event.
“I just cannot believe it,” said Ordonez. “I was going slowly, and suddenly I was in agony on the ground. To miss this race, my home race is such bad luck. I’m not sure what hurts more – missing the race or the pain from my shoulder.
“It will be great to have Jann back with the team, but I wish I were able to share a car with him. Being on the sidelines will be tough, but hopefully, I can help the team off-track in whatever way I can.”