The company made the announcement Wednesday in a tweet that featured the actress' first promotional poster for the brand.
The 30-year-old Ted star wears a gray sweater, skinny jeans and black booties, as she poses in front of Jim Beam's distillery in Clermont, Kentucky for the ad.
The company also released a video of Kunis touring their distillery as she learned about its history while sipping on some bourbon.
"Mila's love of bourbon, her appreciation for the authenticity of our brand, her warm personality and her global relevance to our Make History campaign make her the perfect partner," senior vice president and chief marketing officer at Beam Inc. Kevin George said in a statement.
"As a fan of bourbon and a huge proponent of making history, I am thrilled to be the newest member of the Jim Beam family," Kunis added.
Jim Beam was recently acquired by Japanese whiskey maker Suntory Holdings Limited.