Dawson Willcock, who is 18 months old, was diagnosed with hepatoblastoma, a rare form of liver cancer, in January but chemotherapy has failed to help him.
His parents want to take him to Cincinnati and have started the “Dollar for Dawson” campaign, which has so far raised around £150,000.
They were told the chances of getting the rare cancer are 0.9 in one million.
As part of their desperate bid to raise the funds, parents Wendy and David Willcock, from Sutton, appeared on This Morning and were interviewed by Mr Holmes and his wife Ruth Langsford.
Speaking on the programme, Wendy said: “We hang on to hope – that’s all we have at the moment.”
Dawson is currently being treated at Queen’s Hospital in Romford, which they described as giving “fantastic” treatment but haven’t had much experience in dealing with patients with Hepatoblastoma in the past.
But concluding the interview, Mr Holmes said: “Dawson, come back and see us when you get all your hair back, yeah? When you get better and well and lovely – give us a big wave!” - causing a twitter storm.
One viewer tweeted: “@EamonnHolmes , telling a little lad with cancer to ‘ come back when ya hairs grown ‘ what a heartless , cruel weasel you are #ThisMorning”
While another posted: ““I can’t believe Eamon said to that kid with cancer “Come back when your hair grows back”! I mean, wtf would say such a thing? #ThisMorning”
Although other viewers were supportive and said that the comment was misunderstood and Eamon meant well.
One tweet read: “I watched the interview yesterday, please pass on my love to @EamonnHolmes he meant he wants boy back healthy. Love to Dawson and his fam x”
And another viewer posted: “Poor @EamonnHolmes is under fire I’m sure he meant it in a positive way in as trying to say to the little boy you will recover #ThisMorning”
In a story published on the This Morning wedsite it states that both presenters were ‘left moved’ by Dawson’s visit.
You can support Dawson by donating to the justgiving page which can be found at: