The 36-year-old Red Bull driver has signed a contract with Porsche from the 2014 and will compete in the manufacturer's LMP1 sports prototype at the Le Mans 24 Hours race and World Endurance Championship, the German company said.
Webber has already raced twice at the famous French circuit, finishing runner-up in the GT Championship in 1998
"It's an honour for me to join Porsche at its return to the top category in Le Mans and in the sports car World Endurance Championship and be part of the team," he said in a Porsche statement posted on markwebber.com.
"Porsche has written racing history as a manufacturer and stands for outstanding technology and performance at the highest level.
"I'm very much looking forward to this new challenge after my time in Formula 1. Porsche will undoubtedly set itself very high goals. I can hardly wait to pilot one of the fastest sports cars in the world."
Webber is currently fifth in the Formula One drivers' world championship standings going into Sunday's British Grand Prix at Silverstone.
In the course of his F1 career from 2002, he has achieved 36 podium places, nine race wins and been in pole position 11 times.
Wolfgang Hatz, board member for research and development at Porsche AG, said the company was pleased to have secured his services.
"Mark is without doubt one of the world's best race drivers, he has experience at the Le Mans 24 hour race and on top of that he's been a Porsche enthusiast for many years," he added.
Webber will compete in the new LMP1 car alongside the two current Porsche works driver Timo Bernhard, of Germany, and Romain Dimas, of France, as well as Switzerland's Neel Jani.
Bernhard and Dumas won overall victory at Le Mans in 2007 and 2008.