Ms McCall, a former pupil at Portadown College, won in the 'outstanding period/fantasy' category at the annual Costume Designers Guild Awards held in Los Angeles.
The awards focus on those who work behind the scenes to make stunning costumes for film and television.
Caroline was accompanied to the award show in The Beverly Hills Hilton by Hollywood actress Shirley MacLaine, who plays Martha Levinson in Downton Abbey.
Caroline was head of costume for the show and has previously worked on shows such as Doctor Who and Little Dorrit as well as the Russell Crowe film Robin Hood.
McCall began her career at the Belfast Art College before moving to the Wimbledon School of Art and later training with the BBC.