Pearson made the announcement in a statement, saying its 50 percent stake would be sold for £469 million (€663 million, $730 million).
The sale is being split between The Economist Group itself and Exor, which is controlled by the Agnelli family. The investment firm already had a 4.72 percent stake in the group.
"Exor has agreed to purchase 27.8 percent of The Economist Group's ordinary shares for consideration of £227.5 million (€319 million) and all of the B special shares for consideration of £59.5 million (€83.6 million) from Pearson," the statement said.
"Pearson's remaining ordinary shares will be repurchased by The Economist Group for a total consideration of £182 million (€255 million)."
The sale forms part of major restructuring at Pearson, which wants to focus solely on its education publishing business.
It last month announced plans to sell The Economist Group, which includes also Economist.com and the Economist Intelligence Unit, as it revealed a deal to sell the Financial Times newspaper to Japanese digital media group Nikkei.
"Pearson is now 100 percent focused on our global education strategy," its chief executive John Fallon said in Wednesday's statement.
"The world of education is changing rapidly and we see great opportunity to grow our business through increasing access to high quality learning globally."
Pearson described The Economist as "one of the world's leading weekly business and current affairs publications with a circulation of around 1.6 million".