Activision Blizzard will pay $18 per King share, using $3.6 billion of internal cash and the remainder from an existing credit agreement.
It's expected the deal will close in Spring 2016.
Infamous King's share price has been always under its floatation price.
Prior to this deal, the share price was $15.54, valuing King at $4.7 billion, so Activision Blizzard has paid a premium of over 20 percent.
At the end of its past financial quarter, King had cash of $786 million, revenues of $490 million, and profits of $164 million.
The deal will result in a company which is strong across console, PC and now mobile gaming, boasting over 500 million monthly active players (mainly from King) across 196 countries.
Financially, Activision Blizzard says King will increase its 2016 non-GAAP revenue by around 30 percent.
King will continue to be run as an independent business unit, run up its founder and CEO Riccardo Zacconi.
"We believe that the Acquisition will position us very well for the next phase of our company’s evolution and will bring clear benefits to our players and employees," Zacconi commented.
"We will combine our expertise in mobile and free-to-play with Activision Blizzard’s world-class brands and proven track record of building and sustaining the most successful franchises, to bring the best games in the world to millions of players worldwide."
“The combined revenues and profits solidify our position as the largest, most profitable standalone company in interactive entertainment," said Activision Blizzard CEO Bobby Kotick.