[12][13] For three seasons, from 2012 to 2015, Barnett starred as Peter Mills in the NBC action-drama television series Chicago Fire.
[16][17][18] In the same year, Barnett was cast in the main role of Ben Marshall on the Netflix miniseries, Tales of the City.
[21][22] In July 2019, Barnett joined Arrow for its eighth and final season, portraying John Diggle, Jr.[23][5] His role was announced at a Comic-Con panel.
[25] He enjoys sailing, playing Ms. Pac-Man, classic cars, and is a fan of the White Sox and Chicago Bears.
[27] During filming for Chicago Fire, Barnett lived with co-stars Joe Minoso and Yuri Sardarov.