The first generation Cadillac CT6 premiered at the 2015 New York International Auto Show as the brand's technological flagship sedan. Built upon GM's bespoke Omega platform, its spaceframe structure utilized 64 percent aluminum, resulting in a curb weight lower than mid-size executive cars. Advanced engineering included an Active Chassis Package with active rear-wheel steering, Magnetic Ride Control, a thermal Night Vision system, and an ultra-premium Bose Panaray 34-speaker sound system. The exterior design incorporates distinctive body proportions, sharp character lines, and an iconic front grille featuring the brand's emblem.

Powertrains included a 2.0-liter turbocharged four-cylinder, a 3.6-liter atmospheric V6, a 404-horsepower 3.0-liter twin-turbo V6, and a Plug-in Hybrid variant offering 31 miles of pure electric range. For 2019, Cadillac introduced the performance CT6-V powered by a hand-built 4.2-liter DOHC twin-turbo Blackwing V8 producing 550 horsepower and 627 lb-ft of torque. North American assembly concluded in 2020, while production in China continued through 2022. Standard and optional equipment included advanced active and passive safety systems, multi-zone climate control, and upgraded interior electronics. Standard and optional equipment included advanced active and passive safety systems, multi-zone climate control, and upgraded interior electronics.