Isak Andic, the billionaire founder of high street fashion chain Mango, died in an "accident" on Saturday, according to the company.
Spanish media reported the 71-year-old fell down a ravine to his death while hiking in a mountain range outside Barcelona.
His son was at the scene of the accident, according to the El Pais newspaper.
The Turkish-born businessman founded Mango in Barcelona in 1984 and the chain now operates in 120 countries. Forbes estimated Andic's net worth to be $4.5bn.
Mango CEO Toni Ruiz said in a statement: "His departure leaves a huge void but all of us are, in some way, his legacy and the testimony of his achievements.
"It is up to us, and this is the best tribute we can make to Isak and which we will fulfill, to ensure that Mango continues to be the project that Isak aspired to and of which he would feel proud."