Kenya, Burundi and Madagascar have secured $164.5m (£83.3m) from the World Bank to help roll-out high-speed internet networks.
The World Bank hopes the funding will boost business in the region
The World Bank said the money was being made available to boost business competitiveness in the region.
Eastern and much of southern Africa is the only region in the world not connected to the global broadband infrastructure, the World Bank said.
Kenya will take the lion's share of the funding, with a $114.4m loan.
Madagascar is due to receive a $30m loan, while Burundi will receive a grant worth $20.1m, the World Bank said.
The Washington-based lender said businesses in the three countries were being held back because of the lack of high-speed internet networks.
"University students suffer because they cannot access the internet, and government agencies cannot communicate effectively with each other and their citizens because they are not connected," the bank added.
Currently, the region relies on satellite services for connectivity, with costs among the highest in the world.
But World Bank president Paul Wolfowitz said Africa was becoming increasingly "plugged-in".
"Improving broadband connectivity will add tremendous public value for Africa," he said. "Low-cost, high-quality communications is essential for economic competitiveness."
The boss of Kenyan outsourcing firm KenCall backed the World Bank's move.
"It is absolutely imperative that something be done right now to make bandwidth affordable," said Nicholas Nesbitt, the firm's chief executive.
"Otherwise, we're going to miss a huge opportunity and people are simply going to say that Africa is not ready for these kinds of jobs, is not ready for business."