Mario grew up in Baltimore and other working-class neighborhoods in Baltimore County, Maryland.
He lived with his grandmother, who raised him while his single mother struggled with a drug addiction.
Mario said at the age of four that he wanted to become a singer. His mother supported his dream and bought him a karaoke machine. Mario joined a musical group in Milford Mill Academy with the oldest son of comedian Mo’Nique and best friend Jaye Brebnor and also his younger god sister Chea Tyler. Barrett learned to play the piano and used that skill as the basis for his melodies and songs.
He was discovered at age eleven and signed by producer Troy Patterson,
after singing “I’ll Make Love to You” at a Coppin State College talent show. Mario attended Milford Mill Academy up until the tenth grade where he was inspired by his music teacher, during his early teen years, and was offered a record deal at the age of fourteen, signing with Clive Davis’ J Records.
His musical influences include Stevie Wonder, Marvin Gaye, Sam Cooke, Nat King Cole, Brian McKnight, Boyz II Men, Michael Jackson, Usher, and Joe.
His first introduction to the music industry was the Dr. Dolittle 2 movie soundtrack in 2001. He sang a cover of the Stevie Wonder song “You and I” at Clive’s Grammy party in 2002, and began recording an album.