Mowry was born in Hawaii to Darlene Flowers, who managed her children's careers and also worked as a security guard, and Timothy Mowry, who was in the armed services and later became a police officer in California. His mother is African American and his father is Italian American; the two met in high school in Miami and both joined the military as NCOs. He is the younger brother of the twin sisters Tia Mowry and Tamera Mowry, and is the older brother of Tavior Mowry.

Mowry became known for starring in the television series Smart Guy. He has also appeared in other shows, such as Full House as Teddy, a best friend of Michelle Tanner (Mary-Kate Olsen and Ashley Olsen), and in a number of Disney Channel Original Movies. Mowry also performs the voice of Wade in the Disney Channel animated series Kim Possible. He also guest starred on Disney Channel's original series The Suite Life of Zack and Cody as Brandon. He was the voice of a young Sonic the Hedgehog in the show's Saturday morning incarnation. In 1996, he was a guest star in one of the episodes of Star Trek: Voyager, called "Innocence". He is also a talented vocalist as seen with the Disney Channel Circle of Stars recording of Circle of Life.Tahj was also in the movie "Are We Done Yet?"

Mowry loves to play football and lives in California. He played varsity football at Westlake High School (California). He attends Pepperdine University, after one year of playing football at Savannah State University in Savannah, Georgia. He often wears a W.W.J.D. (What Would Jesus Do) wrist band, even in acting roles. It is seen in nearly every episode of "Smart Guy". (http://imdb.com/name/nm0005254/bio")