The Greek star defeated world No 42 Raphael Collignon 6-4, 6-7(3), 6-3 in the championship match at the clay-court ATP 250 tournament.
In what was the first encounter between the pair, Tsitsipas broke the 24-year-old Belgian five times and lost serve just twice.
Tsitsipas was playing in his 31st ATP Tour final, and his victory saw him claim his 13th title – and first since the 2025 Dubai Championships, which was over 16 months ago.
The 27-year-old, who is a former world No 3, started the Swiss Open ranked 85th, having held a 17-15 record in 2026 before this week.
The two-time Grand Slam finalist’s title run has lifted him 30 places to world No 55 in the Live ATP Rankings.
In an on-court interview with Tennis TV, Tsitsipas said: “It’s a crazy feeling right now.
“I survived a marathon and it was a long week. I played some crazy matches in the last couple of days. It’s crazy that I got four three-setters in a row.
“Every single match felt like it was never finished and somehow I managed to convert every single time and get the victory.
“I couldn’t be more blessed, couldn’t be more happy. It’s been an incredible effort from my side to go out there and do that over and over again.
“Dealt with some pain in the last couple of days, so I had to withstand a lot of different things. Well, the result was obviously the best thing that I would have imagined since the beginning of the week.”
Tsitsipas, who will take a break next week, looked ahead to the North American hard-court swing.
“I’m going back home. I will need one or two days off. It’s been a long week,” he added.
“It’s been a lot of crazy matches and I need some recovery and some rest in order to be ready for the American swing.
“I’m looking forward to trying to do the best possible results at the U.S. swing, and in order to do that I’ll need to be fresh and prepared for a long few weeks on the road.”
Tsitsipas also overcame Alexander Shevchenko, Arthur Rinderknech, Jerome Kym and Ignacio Buse during his run in Gstaad.
