Barnhardt was born in Raleigh, North Carolina, and was raised in Matthews, a suburb of Charlotte.

[1] Barnhardt earned a bachelor of fine arts degree in theater from the University of North Carolina at Greensboro's School of Music, Theatre and Dance in 2015.

In 2017 Barnhardt was cast as Matthew Roe in the second season of the television series Underground and had a small role on the show Scorpion.

In 2019 he was cast as Charlie St. George on the American streaming television series 13 Reasons Why, making his debut in the third season.

[10] The ceremony, officiated by Adam Rippon, was attended by one hundred and thirty guests including Timothy Granaderos, Ross Butler, and Ella Balinska.