The swearing was "an important milestone towards the formation of an inclusive government in Zimbabwe as the people of Zimbabwe march towards national reconciliation, economic recovery, reconstruction and development," said Motlanthe in a statement.
Morgan Tsvangarai and Arthur Mutambara were sworn into their positions as prime minister and vice-prime minister, respectively on Wednesday.
Tsvangarai and Mutambara are joining a unity government with Zimbabwean president Robert Mugabe, who has ruled Zimbabwe since independence from Britain in 1980.
Zimbabwe is in the grip of a deep economic and humanitarian crisis which the international community blames on misrule by Mugabe.
Motlanthe called on the Zimbabwe’s neighbours and the international community to end its sanctions and to "assist [Zimbabwe] as they begin the process of rebuilding their country and addressing a myriad of economic challenges facing their country".
Motlanthe also offered his congratulations to Zimbabwe mediator Thabo Mbeki for his contributions. – SAPA