The film, to be directed by Todd Strauss-Schulson, features Rebel Wilson, Liam Hemsworth, Adam Devine and Priyanka Chopra.
Wilson stars as Natalie, a cynical woman who doesn't believe in love, wakes up one day to find herself trapped inside a romantic comedy.
Gilpin, 30, will play Whitney, Natalie's assistant, and one of her best friends.
The film will release on February 14, 2019.