Up to 20,000 people packed the airport outside the capital Kinshasa to welcome home the man whose supporters describe him as the symbol of unity in the anarchic Central African nation.
A rebel coalition has overwhelmed Zaire's ragged army in the east in the last two months, taking the key towns of Goma, Bukavu and Uvira.
Many thousands more lined the 10 miles from the capital to the airport. Tight security surrounded the homecoming with army sharp-shooters on rooftops at the airport and civil guard troops in trucks along the road from the capital.
The crowds, some wearing imitation leopard-skin hats, surged forward as the plane taxied to a halt.
President Mobutu smiled as he walked down the steps from the aircraft with his wife, Bobi Ladawa, as cheering, drumming, music and chanting resounded around the airport.
Wearing his trade-mark leopard-skin hat, he walked unaided and easily, carrying, as always, a carved walking stick.
Prime Minister Kengo wa Dondo waited at the aircraft steps. A small girl handed the President a huge bouquet of flowers. He shook hands all round and joined in singing the national anthem. The crowded erupted into cheering as he raised his arms in acknowledgement.
Mr Mobutu and his wife later left the airport by car with the fiercely loyal presidential guard protecting their convoy.
The Zairean rebels remained defiant in spite of the return of President Mobutu to Kinshasa, and said they were ready for any counter-attack on eastern Zaire.
One Zairean newspaper said Mr Mobutu plans to stay in Zaire for only two or three weeks, before completing his convalescence in his villa overlooking the Mediterranean.