Johnson tested positive for COVID-19 last Friday and was absent for Sunday's Big Machine Hand Sanitizer 400 in Indianapolis.
"My family is so grateful for the incredible love and support we've received over the last several days," the seven-time NASCAR Cup Series champion said. "I especially want to thank Justin Allgaier for stepping in for me at Indy and being a true pro. I'm excited about getting back to business with my team this weekend."
Allgaier didn't enjoy a good race in Johnson's stead. He was involved in a wreck on pit road on the 16th lap that also knocked out Martin Truex Jr. and Corey LaJoie.
Johnson announced last November he's planning to retire after the 2020 season, giving him one more shot to surpass Richard Petty and Dale Earnhardt for the most Cup Series titles.
The 44-year-old is still looking for his first win in 2020, and he hasn't reached Victory Lane since June 2017. His 390 points place him 15th in the season standings, with 30 points separating him from Austin Dillon in 16th and final playoff spot.
Johnson will hop back inside the No. 48 Chevrolet for Sunday's Quaker State 400 at Kentucky Speedway. He had four top-10 finishes in his first five races at Kentucky but hasn't placed better than 14th since 2015.