"Swisscom is in mourning following the death of its CEO Carsten Schloter," the company said in a statement, adding that the 49-year-old German national was found dead at his home in central Switzerland on Tuesday morning.
"The police are assuming it was a case of suicide," Swisscom said.
"An investigation into the exact circumstances is under way."
The company said the current head of Swisscom Switzerland, Urs Schaeppi, would take over the CEO chair temporarily.
"The board of directors, group executive board and the entire workforce are deeply saddened and pass on their condolences to the family and relatives," board chairman Hansueli Loosli said in the statement.
Schloter, who is reportedly the separated father of three, joined Swisscom in 2000 as head of its mobile phone unit, and took over the helm of the company six years later.
Before Swisscom, he held various positions at Mercedes-Benz France and debitel.
Schloter's death was greeted with shock and consternation in Swiss business and political circles.
Doris Leuthard, Swiss communications minister, paid tribute to Schloter, saying he had successfully positioned Swisscom "in a highly competitive and rapidly changing market".
Peter Grütter, president of the Swiss telecom association, told the SDA news agency he was shocked when he learned the news.
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"In my experience Carsten Schloter was a dynamic person," Grütter said, adding that the Swisscom chief was "direct, open and friendly".
Schloter was credited with promoting the modernization of telecommunications infrastructure in Switzerland.