General Mills, whose food brands include Cheerios and Yoplait, will pay $40 per Blue Buffalo share. That's a 17 percent premium to the pet food company's Thursday closing price of $34.12.
Shares of Blue Buffalo surged more than 5 percent in Friday premarket trading.
Blue Buffalo makes natural foods and treats for dogs and cats. Its Blue brand had approximately $1.28 billion in net sales in fiscal 2017.
"In pet food, as in human food, consumers are seeking more natural and premium products, and we have tremendous respect for how attentive Blue Buffalo has been to the needs of their consumers, pet parents and pets, as they have built their brand," General Mills CEO Jeff Harmening said in a statement.
Minneapolis-based General Mills said once the transaction closes, Blue Buffalo will be run as a new pet operating segment.
Blue Buffalo is expected to keep its Wilton, Connecticut headquarters.
The deal is targeted to close by the end of General Mills' fiscal year 2018.