The move will see the departure of executive chairman Terry Smith, who joined the business in 1970.
The deal is being led by managing director Chris Chivers and finance director Jeremy Vickers. Most of the shares in the group had previously been owned by venture capitalist 3i and Mr Smith.
K&G’s management were backed by Bank of Scotland and Close Brothers, although no figure for the deal has been disclosed.
The firm had revenues of £69 million in 2006. The figure is heading for £80 million this year. Pre-tax profits last year were just under £2 million and the firm employed 279 people.
K&G was formed in 1860 and, along with its head office in Clapham Common, has a regional office and joinery works in Billericay, Essex.