The deal announced Thursday values YES at $3.47 billion, nearly $500 million less than when 21st Century Fox acquired a majority stake in 2014.
FOX Business' Charlie Gasparino first reported on the deal in March.
Disney was required to sell off Fox's regional sports networks as part of its $71 billion deal to acquire Fox's entertainment assets, which triggered Yankee Global Enterprises' right-of-first-refusal to buy back YES Network shares. That deal closed in March.
Sinclair said it would buy 21 regional sports networks in May, but the 80 percent stake in the Yes Network would be sold separately.
Yankee Global Enterprises already held a 20 percent stake in YES.
Yankees Global Enterprises will hold a 26 percent share in YES, with Sinclair owning 20 percent, Amazon getting 15 percent with the right to purchase more, and the rest split among the deal's other investors — RedBird Capital, The Blackstone Group and Mubadala Capital.
"We are excited about partnering with such a renowned franchise as the New York Yankees," commented Chris Ripley, President & CEO of Sinclair. "With this investment, we will have 23 RSN brands, including Marquee with the iconic Chicago Cubs, and 21 RSN brands acquired from the Walt Disney Company last week."
YES is the country's most watched regional sports network and airs Yankees games, Brooklyn Nets basketball games, Major League Soccer's New York City FC games and others, along with more programming specific to the Yankees.
The Associated Press contributed to this article.