Barlow joined Iced Earth after the Night of the Stormrider tour with Blind Guardian in Europe, as a replacement for John Greely. The first album Barlow can be heard on is Burnt Offerings. Barlow left the band in 2003, much to the chagrin of many fans. His reason for leaving was due to personal beliefs related to the September 11 terrorist attacks. He took a look at his life and realized that he wanted to contribute to the "real world" instead of living the illusion of a "rock star." He approached Jon Schaffer with this in late 2002, but Schaffer, known for his persuasive personality, convinced Barlow to stay with the band. When the band recorded The Glorious Burden, Schaffer decided that Barlow's vocals were not what he desired them to be; he believed they lacked the passion and quality that Barlow was known for. He decided to let Barlow go after all and hired Tim Owens, former lead singer of Judas Priest. Barlow became a police officer in the police department in Georgetown, Delaware. He was also a vocalist for the First State Force Band, which is made up of law enforcement members from different departments throughout Delaware. The band performs for schools, aiming to promote positive values through music. On April 13, 2007, Barlow returned to music more fully as the new lead singer of Danish progressive power metal band Pyramaze. Barlow accepted the offer to join Pyramaze because it would allow him to return to the music scene, while still being able maintain his current job. However, on December 11, 2007, it was announced that Barlow had officially re-joined Iced Earth and would be singing on The Crucible of Man and following albums. Pyramaze confirmed that he would remain with them to record their album Immortal, but that their professional relationship would end there. On March 3, 2011, Matt Barlow announced that he will again be leaving Iced Earth after the band finishes its European festival shows, citing his commitment to his family and the need for Iced Earth to tour more as his reasons for retirement. On August 6, Barlow performed his farewell show with Iced Earth at the Wacken Open Air festival. On June 26, 2012, Barlow announced on his Facebook pagethe creation of a new band named Ashes of Ares with former Iced Earth bassist Freddie Vidales and Nevermore drummer Van Williams, posting on YouTube two one-minute teaser videos. The band signed with Nuclear Blast, and the self-titled album released on September 6, 2013. In May 2013, Barlow contributed vocals to American power metal band Artizan's album Ancestral Energy, being featured on the album's final track. On January 1, 2017 a joint project with Jonah Weingarten of Pyramaze named We are Sentinels was announced by Barlow on his Facebook page.
