Team INEOS have announced that sport director Nicolas Portal died suddenly on Tuesday aged only 40.
Former rider Portal reportedly suffered a heart attack at his home in Andorra.
The popular Frenchman ended his racing career in 2010 due to cardiac arrhythmia, but remained with Team Sky after retiring.
Portal oversaw Chris Froome's four Tour de France triumphs and played his part in Egan Bernal winning the yellow jersey last year after Team Sky became Team INEOS.
A Team INEOS statement said: "It is with the greatest sadness that we announce the passing of our much loved team-mate, colleague and friend Nico Portal who died suddenly this afternoon at his home in Andorra.
"We are all overcome with grief at this terrible news and would ask everyone to respect the family's privacy at this difficult time.
"RIP Nico - your spirit will always be with us on the road and you will forever be in our hearts."
Froome was among the riders to pay tribute to Portal.
He tweeted: "My thoughts are with Nico's wife and children tonight. He was the kindest, happiest guy I knew and always lived life to the fullest. Rest In Peace Nico."
Portal competed in seven Grand Tours and won a stage at the 2004 Criterium du Dauphine before such a successful career off the bike.