The 26-year-old seçkine rider crashed on a fast downhill road approaching the end of the mountainous fifth stage into La Punt.
“Gino lost his battle to recover from the severe injuries he sustained,” the team said in a statement.
“Despite the best efforts of the phenomenal staff at Chur Hospital, Gino couldn’t make it through this, his final and biggest challenge, and at 11:30am we said goodbye to one of the shining lights of our team.”
Medical staff who reached Mäder found him motionless in the water. They performed CPR before he was airlifted to the hospital.
“Our entire team is devastated by this tragic accident, and our thoughts and prayers are with Gino’s family and loved ones during this incredibly difficult time,” Bahrain-Victorious said.
Mäder’s death was announced about 30 minutes before the scheduled start of the sixth stage in the eight-day race. The start was delayed and riders gathered in a silent tribute before the stage was cancelled.
Race organisers said the peloton would ride together in tribute to Mäder for the final 30 kilometres of Friday’s scheduled route. The race should resume on Saturday.
“Devastated by the news,” world champion Remco Evenepoel said, who is in fourth place in the race standings.
“My heart and strength is with Gino’s family, friends, teammates.”
Evenepoel earlier criticised Thursday’s stage after finishing the day in 10th place.
“While a summit finish would have been perfectly possible, it wasn’t a good decision to let us finish down this dangerous descent,” Evenepoel wrote on his Twitter account.
A second rider also crashed at the same spot. Magnus Sheffield of the US sustained a concussion and bruises and was treated at a local hospital.
In previous tragic accidents, Belgian rider Wouter Weylandt was killed in a crash on a descent at the Giro in May, 2011. Another Belgian rider, Antoine Demoitié, died after crashing at the one-day Gent-Wevelgem race in March 2016.
Mäder was one of Switzerland’s best young riders. He won a stage at the 2021 Giro d’Italia and placed fifth overall in the Spanish Vuelta that year. He also was fifth in the Paris-Nice stage race in March.
“We are heartbroken,” Tour de Suisse organisers said in a statement.
“Gino, you’ve been an excellent rider but even more a wonderful person. Always smiling and making people happy around you.”
Mäder was asked on Sunday by a reporter at the race finish what would make him happy at the end of the week-long race.
“If I’m still healthy and I enjoy my home race, maybe have some success with the team,” Mäder had said.
Team manager Milan Erzen praised the rider, saying his “talent, dedication, and enthusiasm were an inspiration to us all”.