Gia Matteo is the architect recommended by Elliot Grey to design Anastasia and Christian's future home near the coast in Seattle. She is good-looking: tall, curvaceous, and "well-groomed", with short, "salon-blonde" hair. Kate calls Gia a "social climber"; Christian calls her a "sexual predator". Ana gives her the nickname "Miss-Provocative-And-Unfortunately-Good-At-Her-Job".
Although Ana does not particularly like Gia, she admits that she is extremely good architect, and is very pleased with her final plans for the house. She is the tertiary antagonist in Fifty Shades Freed.
During her consultations with Christian and Ana, Gia makes small, flirty gestures towards Christian; in particular, she frequently touches his arm. This makes Ana extremely jealous, but she can also tell that the touching makes Christian very uncomfortable. While Christian is out of the room momentarily, Ana threatens to fire Gia if she does not stop flirting with Christian. Not wanting to jeopardize an extremely valuable contract, Gia backs off.
Gia and Elliot had a short-lived fling about a year before he met Kate Kavanagh. When on vacation in Aspen, Ana sees Elliot meet briefly with Gia and becomes suspicious. However, it turns out to be coincidence: Gia owns property in Aspen and went there to concentrate on her work for the Greys, and Elliot's cagey behavior was merely nervousness about proposing to Kate.
In the film version, Gia attends the wedding of Christian and Anastasia.
Actress Arielle Kebbel portrays Gia in Fifty Shades Freed.