The Adidas-sponsored athlete cited fears over the Zika virus outbreak in the Brazilian coastal city.
“This was not an easy decision for me,” Johnson said in a statement released by his representatives on Friday. “But my concerns about the Zika virus cannot be ignored.”
The Zika virus is associated with transmission from mosquito bites, and while some adults suffer mild symptoms or fever, it can escalate to neurological problems, paralysis and blindness. Some women who have been infected have delivered babies with severe birth defects. Men can pass the virus on to women.
The disease has no cure.
Johnson and his fiancee, Paulina Gretzky, have 18-month-old son Tatum and “plan to have more children,” he added.
“I feel it would be irresponsible to put myself, her or our family at risk,” Johnson continued. “I believe I am making the right decision for me and, most importantly, my family. While I am sure some will be critical of my decision, my hope is that most will understand and support it.”
Johnson recently won the U.S. Open wearing his Adidas Tour360 Boost cleats, and claimed victory at the World Golf Championship last week.
He is the seventh world-ranked golfer to drop out of the Rio Games since the sport returned after 112 years.
Echoing a similar explanation, pro golfer Rory McIlroy announced his split from Team Ireland in June, joining a chorus of other top athletes.
“After speaking with those closest to me, I’ve come to realize that my health, and my family’s health, comes before anything else,” McIlroy said in a statement. “Even though the risk of infection from the Zika virus is considered low, it is a risk nonetheless and a risk I am unwilling to take.”