The 45-year-old was forced to vacate the cockpit of his 23XI Racing Toyota last July, just two months after taking the 34th win of his career at Kansas, when he suffered a concussion at Pocono.
In October, he announced that he would not return as a full-time driver in 2023, allowing Tyler Reddick to make his switch from Richard Childress Racing one year earlier than planned.
There was still hope that Busch could be back in select starts, with 23XI Racing co-owner Denny Hamlin leaving the door open for Busch to drive for the team again. He has since remained close to the action, mentoring both Reddick and Bubba Wallace, while also serving as a brand ambassador for Monster Energy.
But Busch revealed on Saturday ahead of the final race of the regular season at Daytona that the 2017 Daytona 500 winner would not be adding to his 776 Cup starts, dating back to 2000.
In a video announcing his retirement, Busch explained that the decision had been made in consultation with his medical team.
"Sometimes father time can catch up to your dreams," he said.
"My incredible team of doctors and I have come to the conclusion that at this point in my recovery there are just too many obstacles for me to overcome and get back to 100%.
"So after 23 years behind the wheel and 45 years of living and breathing this dream, I am officially announcing my retirement from NASCAR Cup Series competition."
Source: Autosport