Charlene, who married Prince Albert, ruler of Monaco, in a lavish ceremony in 2011, was pictured holding a dog in the principality with her family.
Her stay in South Africa, where she grew up, sparked speculation about a possible split within 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.
She had arrived in nearby Nice on a private jet in the morning, it added.
Photos showed Charlene wearing a protective face mask surrounded by her husband and children in front of the white stairs of the palace.
In September, the princess was hospitalized in South Africa for treatment for an ear, nose and throat infection that caused her to collapse.
The royal palace said on Monday that Charlene – who swam to South Africa during the 2000 Olympics – “had been held up in South Africa due to medical problems”.