The music-focused drama Empire made a massive splash when it debuted on Fox in January 2015, and a large part of the appeal for many people was Taraji P. Henson and her work as the take no bullshit mother / mogul, Cookie.
It had always made sense, with the popularity of the character, to do something more with her, and while plans for a prequel spinoff focused on a younger version of the character were eventually abandoned, when Empire was drawing to a close it was decided that Henson could simply take Cookie elsewhere to lead her own show.