Roberts was pictured while she was on a visit to the Old Navy Flip-Flop vending machine in Los Angeles.
The actress dyed her hair brown from a reddish brown hue, which he did last year, reported US magazine.
The 'Wild Child' star's last major hair makeover was in January, when she cut her long blonde hair into a chic bob.
The 23-year-old actress, who is engaged to actor Evan Peters, is the latest celebrity to show off a dramatic hair color transformation.