Based in Shanagarry, Co Cork, Cully and Sully makes a range of soups, pies and hotpots and supplies all the major food retailers in Ireland.
Co-founder Cullen Allen - or Cully for short - said he and business partner Colum O'Sullivan will stay on at the company and hope to see it crack Europe and the US.
"Between the jigs and the reels we got talking to these guys and they offered basically to buy out our company, buy 100% of it" he said.
"But also we see huge opportunity for us to get our product into the States and into Europe actually as well, which is something that we've been really struggling with up to this point.
"So hopefully this will give us a bit more credibility - or whatever it is you need - to try and make those things and get the brand to grow internationally," he added.
The duo will continue to manage all aspects of Cully & Sully, reporting to Rob Burnett, Chief Executive Officer, Hain Daniels Group.
Headquartered in Melville, New York, Hain Celestial is a leading natural and organic food and personal care products company in North America and Europe.
"We are pleased to be expanding our international presence into Ireland with Cully & Sully, a leading chilled brand that has delivered consistent, profitable growth since 2004," said Irwin D. Simon, Founder, President and Chief Executive Officer of Hain Celestial in a company statement.
"We also welcome two energetic, creative entrepreneurs, Cully and Sully, to the Hain Celestial Europe team."