Johnson will race for a 19th season next year in his No. 48 Chevrolet, ESPN reported.
In a black-and-white video posted on Twitter, Johnson said he was "so thankful for 18 incredible years" on the NASCAR circuit.
"I am so thankful for 18 incredible years of racing in NASCAR," Johnson said in the black-and-white video comprising highlights from his career. "This sport has been good to me and allowed me to do something I truly love. I showed up chasing a dream and achieved more than I ever thought possible. I'm looking forward to next season and celebrating what will be my last year as a full-time NASCAR Cup driver. I know what this team is capable of and I hope 2020 is one of the best yet."
Johnson, 44, spent his career racing for Hendrick Motorsports since he debuted in 2011, NASCAR.com reported.
Johnson has 83 career victories, tied with Cale Yarborough for sixth on NASCAR's all-time list, ESPN reported. He is tied with Richard Petty and Dale Earnhardt Sr. for the most NASCAR series titles.
"NASCAR history will always hold Jimmie Johnson in the highest regard, for his hard-charging success on the racetrack and the way he conducted himself as a champion off the track," NASCAR Chairman and CEO Jim France said in a statement. "This remarkable seven-time champion – through his competitive spirit, immense talent and sportsmanship – has made NASCAR a better sport. On behalf of my family and the entire NASCAR community, I thank Jimmie for his dedication to NASCAR and, along with his legions of fans, wish him all the best in his final season. I look forward to watching him race for wins and an eighth NASCAR Cup Championship in 2020."