As one of the four contributing voices to the Backstreet Boys, Howie is notable for his high falsetto. Being the countertenor, he has usually sung the highest harmony in the choruses, and is notable for being a normal choice for ballads, where he has taken over some slow-tempoed lines ('I Want It That Way', 'Drowning', 'The Answer To Our Life', 'The Perfect Fan', 'Show Me The Meaning Of Being Lonely').
Howie has sung lead on several Backstreet Boys tracks, the most notable being "Spanish Eyes" from the Millennium album and two tracks that he penned himself: "What Makes You Different (Makes You Beautiful)" and "How Did I Fall In Love With You" sung with fellow band member, Brian(Black and Blue).
Still he's mostly the official two-part harmoniser of the group, often supporting either Brian, Nick or AJ while they're singing solo (e.g. 'Incomplete' chorus, 'Larger Than Life' pre-chorus, some parts of 'I Still', 'Shape Of My Heart' pre-choruses). However, on the latest album "Unbreakable," Howie's voice has been more noticeable in many of the songs; mostly due Kevin Richardson's absence in the album. Moreover, Howie has replaced most of Kevin's parts in live concerts when they perform old songs, such as in an I Want It That Way performance in Japan, even though they have completely different vocal ranges.
As of late, Howie has also been working as a producer/mentor to singer/song-writer George Nozuka. On the Backstreet Boys Unbreakable tour in 2008, he sang a new solo song entitled "She's Like the Sun".
Dorough has also guest-starred in the television series Sabrina, the Teenage Witch in the episode "The Big Head" as an egotistic rock star named Strum.
He also guest starred on an episode of Roswell.
Dorough is reported to have done a collaboration with an extremely famous Philippine singer, Sarah Geronimo; known as the Pop Star Princess, for Geronimo's upcoming album this 2008. Entitled Just Me... Sarah.
In June 2008, Howie teamed up with Rock Your Religion to help conquer Lupus through sales of “The Howie Pendant by Rock Your Religion.” Proceeds from “The Howie Pendant by Rock Your Religion” sales will be donated to the Dorough Lupus Foundation, established in memoriam of Howie’s sister, Caroline Dorough-Cochran, who lost her life to the devastating disease.