Jesse McCartney was 19 in Horton Hears a Who! when he played the character 'JoJo (voice)'.
That was over 16 years ago in 2008.
Today he is 37, and has starred in 28 movies in total, 21 of those since Horton Hears a Who! was released.
In Horton Hears a Who!, I think Jesse McCartney looks: