The pair beat out fellow finalists (and former champs) actress Kelly Monaco and Olympian Shawn Johnson to claim the sparkly mirror-ball trophy.
Fellow contestants on the show's first "all-star" season hoisted the new winners into the air as confetti rained down inside the "Dancing With the Stars" ballroom.
On the eve of the final competition, Rycroft said she felt confident and excited.
"I want to feel like a champion," she said.
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.
Six of those contestants — Johnson, Monaco, Lachey, Ohno, Smith and Castroneves — were previous "Dancing" winners.
Rycroft and Dovolani came into the final contest 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 had less than an hour to prepare.
Rycroft was a contestant on "The Bachelor" in 2009 and first appeared on "Dancing With the Stars" that same year. The 29-year-old also starred in a reality series earlier this year, "Melissa & Tye," about her marriage to Tye Strickland and their move to Hollywood so she could pursue an entertainment career.