Stebe was the lowest-ranked finalist on the ATP tour for a decade, and came to the Alpine resort of Gstaad without a match win since 2017.
The 31-year-old Ramos-Vinolas got his second career title without dropping a set all week. The clay-court specialist's previous title was in 2016 at Bastad, Sweden.
A rain-delayed start Sunday gave Stebe extra time to recover from back-to-back three-set wins on Saturday in the quarterfinals and semifinals.
The 28-year-old German had two surgeries last year on his right wrist, and also missed the 2014 season due to injuries.
The previously lowest-ranked men's finalist was No. 866 Raemon Sluiter, who was runner-up at the 's-Hertogenbosch grass-court event in 2009.