Vodacom, a unit of Britain's Vodafone, said the deal will help the company to "accelerate broadband connectivity" in South Africa, which has been lagging behind emerging market-peers.
Neotel, which majority-owned by India's Tata Communications has been in business for seven years, operating mainly in urban areas, in a sector which is still dominated by state-backed provider Telkom.
Vodacom group chief executive Shameel Joob said the 100 percent buyout fitted the company's business aim of growing its data business, where the company has seen growth in recent years.
It said 7.2 million customers in its main market, South Africa, were using smartphones.
The company also has operations elsewhere in Africa -- Mozambique, Nigeria, Lesotho, Tanzania and the Democratic Republic of Congo.
The transaction was still to be approved by competition authorities.