Swiss media reported that Senn had died at his vacation home in Klosters, near Davos, in eastern Switzerland.
“It is with great shock and sadness that we must inform you of the sudden death of Martin Senn. His family informed us that Martin took his life last Friday,” the company said in a statement released on Monday.
“With the passing of Martin, we lose not only a highly valued former chief executive and colleague but also a close friend,” it added.
Senn, 59, was a Swiss national who had joined Zurich Insurance as chief investment officer in 2006 and rose to the chief executive role in 2010. He stepped down last year after a difficult period for the company.
In February, Zurich reported a larger-than-expected loss for the fourth quarter of 2015 and said it was implementing a cost-cutting and efficiency drive targeting savings of over $1bn (£700m, €900m) that would impact around 8,000 or 15% of its 55,000 employees by the end of 2018.
Zurich has been under pressure since it was forced to call off a planned acquisition of UK-based RSA Insurance Group last September as it struggled to re-build itself after suffering heavy losses incurred by the deadly explosions in the port of Tianjin in China the previous month.
The company is still battling to turn itself around, reporting a drop in net profits for the first quarter, when operating profits fell 23% in general insurance and decreased marginally in the company’s Global Life business.
It now has a new chief executive in Mario Greco, the former head of Italian insurer Generali, who returned to head Zurich Insurance and lead the turnaround effort in March.
Senn's death comes less than three years after the company's former chief financial officer Pierre Wauthier, also committed suicide.