The takeover of the UK's biggest pet store chain comes after a fiercely competitive bidding duel between some of the biggest private equity groups, after its owner, private equity firm Bridgepoint, decided not to go for an IPO.
Pets at Home was valued at £700m, with some suitors placing initial bids greater than £800m.
The company sells pet food and accessories through its chain of over 250 stores. After acquisition, it will stay under the leadership of CEO Matt Davies, who sees potential for up to 400 out-of-town stores.
Pets at Home generates the bulk of its sales from pet accessories. It was seen as an attractive buy because of its growth potential and the lack of much competition in the area.
Bridgepoint bought Pets at Home for £230m in 2004. KKR's price is at the top end of the IPO valuation range.
The equity firm's other retail investments include chains such as Toys R Us and Alliance Boots.