The wedding on Saturday night attracted 100 guests, including Prince Albert of Monaco, the ATS news agency reported.
Police, including those from Monte Carlo, installed a security perimeter around the Roman church to prevent curious onlookers and paparazzi from getting too close to the event.
Casiraghi, 29, and Santo Domingo, a 30-year-old heiress to a Columbian industrial fortune (airline, media and telcom businesses), were married civilly last August in Monaco.
They also have a son, who was born March 21st 2013 in London.
The royal house of Monaco refused to comment on the marriage, which was announced earlier this week by gossip magazine Hello.
According to Hello, Tatiana was very attached to the region around Rougement, which is close to Gstaad, because she spent the first 15 years of her life at the mountain resort town in the canton of Bern.
After the wedding ceremony, ATS reported the assembled guests were invited for dinner at Gstaad, noted as the official residence of such personalities as French rock star Johnny Halliday and movie director Roman Polanski, who take advantage of its low tax rates.