"I don't feel confident that I can continue to devote the time needed to thrive in my role," Johnson said in a statement released by the network on Thursday.
Since retiring from basketball, Johnson has been successful in business, investing in movie theaters, a production company and restaurants. He is also part of the ownership group that agreed to buy the Los Angeles Dodgers in March 2012.
In addition, he has been an activist in the fight against HIV after being diagnosed with the virus in 1991.
Johnson joined ESPN's "NBA Countdown" in 2011.
"I will always feel a strong connection to the ESPN family and I enjoyed working with them very much," Johnson said.
The Associated Press contributed to this report.