King Charles III honoured the 80-year-old actor, director and playwright for his services to drama, it said. Kani received the award last week, the British High Commissioner said on X.
Kani launched his acting career in the 1960s, during the era of white-minority rule in South Africa.
He and playwright Athol Fugard defied apartheid-era racial segregation laws by meeting in secret and staging rehearsals in classrooms and garages, under the harassment of police.
In 1975 Kani won a Tony award with fellow performer Winston Ntshona for their New York performance of Fugard's 1972 play "Sizwe Banzi is Dead".
More recently, Kani voiced the wise mandrill Rafiki in the 2019 remake of "The Lion King". He played T'Chaka in the Marvel studios superhero films "Captain America: Civil War" (2016) and "Black Panther" (2018).
"His career, spanning decades, has not only shaped the landscape of South African theatre but has also brought the richness of our cultural heritage to the world," the government said in a statement.
"Government and the people of South Africa celebrate this achievement with Dr Kani as his contribution has not only enriched the South African culture but has also resonated with audiences worldwide."
