The former 98 Degrees group member, who is about to become a father, let out a war whoop when asked for his reaction to the win.
"It's an ugly trophy but you still want to win," Lachey said.
"I knew I was clumsy," Rice said in thanking partner Anna Trebunskaya for turning him into a dancer.
"I'm very happy I decided to take the chance," Rice added.
Wrestler Stacy Keibler and her partner Tony Dovolani were eliminated just before the final round even though they were among the judges' favorites. Keibler earned her highest scores for a series of Latin dances, which had judge Bruno Tonioli describing her as a "weapon of mass seduction."
In earlier rounds, actress Lisa Rinna, actor George Hamilton, newscaster Giselle Fernandez, rapper P. Miller (Master P), actress Tia Carrere, sportscaster Kenny Mayne and actress Tatum O'Neal were eliminated.
The competition began Jan. 5 with 10 couples. The program is modeled on the BBC's "Strictly Come Dancing."
"General Hospital" actress Kelly Monaco won the first competition last summer.