Jay DeMarcus is an American bassist, vocalist, pianist, record producer and songwriter. He is a member of the country group Rascal Flatts.


DeMarcus was born in Columbus, Ohio. He graduated from the Tree of Life Christian School and Fort Hayes Metropolitan Education Center in Columbus while living with his mother and sister. He also has a half-sister from his father's side of the family. DeMarcus attended Lee College in Cleveland, Tennessee, from 1990 to 1992. At the time, he traveled and performed as a keyboard player in the Christian music group New Harvest, led by Danny Murray.


DeMarcus co-founded the contemporary Christian music group East to West and moved to Nashville, Tennessee, in 1993. In 1997, after East to West disbanded, he called his second cousin, Gary LeVox, with whom he played when they were younger, and convinced him to come to Nashville and provide some harmonies on Michael English's album Gospel, which he was producing. They engineered the album together, and became English's back-up band and road manager. The album was nominated for the Dove Award for Inspirational Song of the Year.


In addition to producing for English, he has also produced albums for James Otto, Jo Dee Messina, Austins Bridge and others. He produced the 2006 release for the band Chicago titled, Chicago XXX. He soon became bandleader for Chely Wright. Eventually, he met Joe Don who is now the group's other member. DeMarcus called Joe Don to fill in for a guitarist who had left the band one night.


On March 4, 2010, DeMarcus and his band mates were guest stars on CSI: Crime Scene Investigation, appearing as themselves. In the episode titled "Unshockable" (10.14), he is electro-shocked by his bass guitar during a performance at a Vegas club, leaving him with total amnesia which he recovers from at the end of the episode. DeMarcus has continued to explore his acting career, appearing in the film A Country Christmas, as well as episodes of ABC's Nashville and Lifetime's Drop Dead Diva.

In October 2018, DeMarcus founded the label Red Street Records, an independent Christian music label