A message on Twain's website says the couple were wed in Rincon with 40 close family and friends in attendance.
Twain and Thiebaud announced their engagement last month.
Twain first confirmed in August 2009 that she was dating Thiebaud after her divorce from Robert "Mutt" Lange - who allegedly had an affair with Twain's best friend and Thiebaud's wife, Marie-Anne Thiebaud.
The 45-year-old singer from Ontario, Canada, said she reached out to Frederic Thiebaud in the aftermath, writing on her website last year that she had found "a dear friend and true gentleman."
Twain, who has stepped away from the spotlight the last few years, has an autobiography due out in the spring and is scheduled to have her own show on Oprah Winfrey's television network.
