The show, which returns for its sixth series this autumn, commands an average of 7.8m viewers, more than 40% of whom are children, according to BARB.
A spokeswoman for Alcohol Concern said: 'We would not welcome an alcohol company sponsoring a show that is either targeted at children or has such a high percentage of children watching.
'The people producing these programmes and the drinks companies have a duty to think about who they are targeting and who the viewers are.'
Rooney Anand, Greene King's chief executive, defended the move, saying that the show attracts viewers who are a close fit with Greene King's customer base, which includes families that can visit its child-friendly Hungry Horse chain.
He added: 'It is a younger demographic than you might expect. But we see ourselves as a responsible retailer and we conveyed this to ITV.'
As part of the deal, the brewer, which also owns ale brands Old Speckled Hen and Greene King IPA, will get 80 seconds of airtime per show, as well as exposure on ITV2 and branding on the ITV website. Break-bumpers, by MCBD, feature the tagline 'Greene King, the sign of a great pub'.
A scratchcard promotion will run in 1350 Greene King Pubs, offering consumers the chance the win the products in the programme's ad breaks.