De Jongh has penned a three-year contract with Phunya Sele Sele.
The 28-year-old made 25 appearances last term for Stars, who have been relegated to the National First Division and renamed Cape Umoya United ahead of their move to the Mother City.
De Jongh is the first signing made by Celtic's new coach Steve Komphela. The pair previously worked together at Maritzburg United.
His arrival in the City of Roses will help offset the imminent departure of Namibia international Deon Hotto to Bidvest Wits.
— Bloemfontein Celtic (@Bloem_Celtic) June 29, 2018