Rycroft and Dovolani came into the final contest Tuesday with a pair of perfect scores. Those points were combined with viewer votes and a last set of judges' scores for an "instant dance," for which they earned 28.5 out of 30 points to a Samba to "Life is a Highway."
"This is so cool and so unexpected," Rycroft said as she held her prize. "You have to thank the fans out there because this is from them. It wouldn't have been possible to beat some of the people that we did in this competition without the audience. It's been such a great ride."
Rycroft beat out fellow finalists - and former champions - Olympian Shawn Johnson, who came in second place, and actress Kelly Monaco.
"We had so much fun, we put everything out on the dance floor," Johnson said. "All you have to do is look at Tony and Melissa's faces and how much it means to them. It's a perfect ending."
"I don't feel like I've lost out on anything," Monaco added. "There are three women and each and everyone one of us were different and you can't compare that. I feel like there were three winners in this competition."
Rycroft, 29, was a contestant on "The Bachelor" in 2009 and first appeared on "Dancing With the Stars" that same year. She also starred in a reality series earlier this year, "Melissa & Tye."
Tuesday's two-hour season finale featured performances by the three finalists and each of the returning cast members: actors Pamela Anderson, Sabrina Bryan, Kirstie Alley and Gilles Marini; singers Joey Fatone and Drew Lachey; race car driver Helio Castroneves; reality TV star Bristol Palin; Olympic skater Apolo Anton Ohno; and football star Emmitt Smith.See photos of the season finale of "Dancing With The Stars: All-Stars"
The Associated Press contributed to this report.