Fletcher, nicknamed “Fletch”, founded the group in Basildon, Essex, in 1980 and was inducted into the Rock and Roll Hall of Fame two years ago.
The band, whose hits include Enjoy The Silence, Personal Jesus and Just Can’t Get Enough, have enjoyed decades of popular and critical acclaim.
In a statement, Depeche Mode said: “We are shocked and filled with overwhelming sadness with the untimely passing of our dear friend, family member and bandmate.
“Fletch had a true heart of gold and was always there when you needed support, a lively conversation, a good laugh, or a cold pint.”
Lol Tolhurst, drummer with The Cure, shared a heartfelt tribute to Andy Fletcher after news of his death broke.
“Very sad news today. Andy Fletcher of Depeche Mode has passed,” he tweeted.
“I knew Andy and considered him a friend. We crossed many of the same pathways as younger men.
“My heart goes out to his family, bandmates, and DM fans. RIP Fletch.”