The executive was poached from Infiniti to help revitalize GM's struggling luxury brand.
Cadillac CEO Johan de Nysschen has left the company, replaced by General Motors Canada president Steve Carlisle.
"We appreciate Johan's efforts over the last four years in setting a stronger foundation for Cadillac," GM said in a statement. "Looking forward, the world is changing rapidly, and, beginning with the launch of the new XT4, it is paramount that we capitalize immediately on the opportunities that arise from this rate of change. This move will further accelerate our efforts in that regard."
De Nysschen was poached from Infiniti in 2014 after Cadillac had been left out of the broader double-digit growth in the luxury segment. The new chief attempted to make Cadillac a more distinct entity, establishing a new headquarters in a trendy New York City neighborhood.
The former Audi executive intended to transform Cadillac into a competitive luxury brand, rather than a discount alternative to German and Japanese rivals. He led a naming shift, starting with the flagship CT6 sedan. The brand appeared slow to expand its SUV lineup, however, as buyers continued to shift away from cars.
Cadillac's US sales fell by nearly five percent in 2016 and nine percent in 2017. Ongoing growth for the XT5 has helped the brand recover slightly in the first three months of 2018, but dealers will have to wait until fall before the XT4 arrives.
A GM lifer, Carlisle has been praised for leading a "resurgence of the GM Canada franchise."