The King will meet university students and will be offered a new High Chief title in the village of Moata’a.
The Queen, meanwhile, will pay a visit to a church school and a women’s forum focusing on domestic abuse.
They will both spend time at the Samoan Cultural Village, which celebrates traditional arts, crafts, culture, enterprise and sport.
On Friday, the King will spend the day at the CHOGM, which brings together delegations from 56 countries in Africa, the Caribbean and Americas, Europe, Asia and the Pacific.
He will deliver a speech, welcome new heads of government and attend a celebratory dinner in one of his most significant days of duty since his cancer diagnosis.