Legallo, 34, proposed with a diamond by French jewelry designer Jean Dousset of Beverly Hills, according to USA Today. Adams, 33, met Legallo, an actor and artist, in acting class in 2001.
Adams has said about boyfriend in the past, "I'm really lucky because he's not competitive with me. He supports and embraces my success as mine. And he has his own goals for himself, but he never makes my success his failure."
USA Today says the couple plan to marry sometime next year.