The food chain said on Twitter it was apologising for “any offence caused as a result of this partnership” after giving away a pizza with a purchase of the paper.
Stop Funding Hate raised concerns that Pizza Hut was running a promotion in The Sun - one of several British tabloids the campaign group is urging advertisers to sever ties with.
Pizza Hut said on Sunday night that the “aim” of the offer “was simply to give our customers the chance to enjoy a free pizza to share with their family and friends”.
At the weekend Stop Funding Hate urged “concerned” supporters to get in touch with Pizza Hut.
“Please leave a polite and friendly comment,” Stop Funding Hate wrote on Facebook in a post that’s had nearly 900 reactions.
Last month, Paperchase apologised after a weekend promotion by the stationery company in the Daily Mail sparked a similar response.
Paperchase issued a statement saying it had “listened” to customers and was “truly sorry”, adding: “We won’t ever do it again.”
Although Paperchase’s apology was widely shared on social media, Stop Funding Hate’s original post informing followers about the partnership only received about 550 reactions and was shared 94 times.
The campaign group claimed victory after the Paperchase response, and had highlighted Pizza Hut’s advertising in The Sun.
Stop Funding Hate said in a statement to HuffPost UK on Monday: “With growing concern that the hate in our media is fuelling hate crime on our streets, is it any wonder so many of us don’t want to subsidise this through our shopping?
“We’d urge the Sun to reflect on why so many feel attacked by its hostile coverage, and why brands might want to distance themselves.
“As always, we encourage everyone who supports Stop Funding Hate to keep it civil and polite - both towards brands and the media outlets we’re challenging.”
But on Monday, Pizza Hut was still named in Stop Funding Hate’s list of advertisers in The Sun.
The promotion still appeared to be continuing on Sunday afternoon.
The Sun has faced a boycott from a large number of people in Liverpool over its inflammatory coverage of the Hillsborough disaster.
Feelings against the paper in Merseyside are so strong that one local branch said they would not be honouring the deal with The Sun.
In a Facebook post written on Sunday, Pizza Hut Delivery in East Prescot Road, Liverpool, stated: “We are passionate in supporting justice for the 96.
“As a way of an apology please quote ‘you’ll never walk alone’ to gan 50% off your order.”
Earlier in the weekend, many people from Liverpool criticised Pizza Hut for running the promotion with The Sun.
But some people were baffled by Pizza Hut’s decision.
HuffPost UK has contacted Pizza Hut and The Sun for comment.
Stop Funding Hate’s campaign has been trying to convince brands to pull their advertising from The Sun, The Daily Mail and the Express, saying the papers use “fear and division to sell more papers” and demonise groups such as refugees and migrants.
The Paperchase promotion offered Daily Mail readers two free rolls of Christmas wrapping paper, worth £4.75, from the store.
The Daily Mail accused Paperchase of allowing itself to be “bullied into apologising” and described Stop Funding Hate as “a small group of hard left Corbynist individuals seeking to suppress legitimate debate and impose their views on the media”.
Responding to the Daily Mail’s comments, a Stop Funding Hate spokesperson said: “Stop Funding Hate is a non-partisan human rights campaign focussed solely on the issues of hate speech, media hate and discrimination.
“Stop Funding Hate is not linked to, or aligned to, any political party. We are funded by voluntary donations from thousands of members of the public.
“We are proud to have supporters from a wide range of backgrounds and political viewpoints, including many people who do not think of themselves as especially ‘political’.
“No amount of name-calling by the Daily Mail will change this basic fact: People who are affected by media hate, or concerned about media hate, have a right to ask the companies they shop with not to fund newspapers that demonise and discriminate.”