Underwood, 27, and Fisher, 30, tied the knot under a tent at Ritz Carlton Reynolds Plantation in Greensboro, Georgia, before 250 friends and family.
The ceremony, which cost more than $500,000 according to RadarOnline, featured classical music and the couple's favorite Bible readings.
"American Idol" winner Underwood wore a Chantilly lace dress by fashion designer Monique Lhuillier, who also created the bridesmaids' dresses, People magazine reported.
"We could not feel more blessed to have found each other and to have shared this day with our friends and family that mean so much to us!" the newlyweds told People in a statement, signing their names "Mike & Carrie Fisher."
The couple kept their wedding location secret until the 11th hour -- even to guests, who only knew which southern U.S. airport to head to before the ceremony, the New York Post reported. Guests were transported from the airport to the wedding location by either private jet or limos.
Underwood was reported to be seeking $2 million for the photo rights to the event and is believed to have struck a deal with a weekly magazine.
Fisher popped the question to Underwood on Dec. 20, after courting for a year.