The hand-cooked crisp maker, which was founded on a Herefordshire farm in 2002, has seen revenues soar since it was taken over by Bahrain-based investment company Investcorp three years ago.
Tyrrells, which has expanded rapidly internationally, has raked in £84m in revenues over the past 12 months. Global revenues from markets such as Germany and Australia now account for 40% of its sales.
The deal will see chief executive David Milner stay on as Amplify's international president.
Mr Milner said: "This is a terrific deal for Tyrrells and the team who have delivered a stellar performance over the last few years.
"As a small, UK farm-based business it is a tremendous achievement to be now part of a US publicly-traded company with the international reach to make Tyrrells a global brand".
Amplify, best known for its SkinnyPop brand in the US, is a major player in the snacking category in the US.
The Tyrrells stable of products include potato, vegetable and crinkle cut crisps and premium popcorn named ‘posh corn’.
Amplify chief executive Tom Ennis said: "Together we plan to capitalise on each company's market leadership and sales force capabilities to drive higher revenue growth than either company could independently accomplish".
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