The four-time Olympic champion said he had a Transient Ischemic Attack (TIA) last week but was subsequently cleared of any heart issues.
In a series of tweets, the 50-year-old sprinter said: “Last week I rather surprisingly suffered what’s known as a Transient Ischemic Attack or mini-stroke.
“The good news is I’m back at home with my family, cleared of any heart issues and have already made great progress on my road to a full recovery.”
He added: “It seems these things can affect anyone, even the once fastest man in the world! I’m no stranger to a good exercise plan and have thrown myself into it with my usual focus and determination.
“In these situations being a former athlete has really helped with mindset but also a reminder that you need to take [care] of yourself.”
Johnson told fans he would post updates on Twitter and directed people to the Stroke Association website.
The NHS says mini-strokes are caused by a temporary disruption in blood supply to part of the brain.
They cause similar symptoms to strokes, but don’t usually last as long as the symptoms clear in anywhere from a few minutes to 24 hours.
Johnson became the only male athlete to win the 200m and 400m at the same Olympics in 1996. He also has eight world championship gold medals.
He now lives in Malibu, California.