Charlene, who married Monaco’s ruler Prince Albert in 2011 in a lavish ceremony, was pictured walking a dog in the principality with her family.
Her stay in South Africa, where she grew up, sparked speculation about a potential rift inside the royal couple — a claim the family denied.
“Princess Charlene has finally been reunited in Monaco with her husband prince Albert and children prince Jacques and princess Gabriella,” Monaco’s royal palace said on Instagram.
She had arrived on a private jet in nearby Nice in the morning, it added.
Photographs showed Charlene wearing a protective face mask surrounded by her husband and children in front of the palace’s white stairways.
In September, the princess was admitted to hospital in South Africa for treatment for an ear, nose and throat infection which led her to collapse.
The royal palace said on Monday that Charlene — who swam for South Africa at the 2000 Olympic Games — had been “held up in South Africa due to medical issues.”