The Jackson family patriarch, whose kids include Janet Jackson and the late Michael Jackson, endured the health setback on his 87th birthday while in Sao Paulo, Brazil on July 26, reported Us magazine.
Jackson was admitted to Albert Einstein Hospital after feeling dizzy and losing his vision. He is still undergoing tests.
Just hours earlier, Janet posted a sweet message to her father.
"Wishing my Father, @Joe5Jackson a Happy Birthday," the "No Sleeep" singer, 49, tweeted.
"I want to tell the world, I love and honour you."
Joe has reportedly suffered three previous strokes. The former Jackson 5 manager suffered a mild stroke in November 2012. At the time, he complained of having pains in his head and had difficulty standing. He stayed under observation at a Las Vegas hospital.