Tim Schofield was suddenly taken ill before the latest edition of the ITV daytime show, meaning that Phillip missed it so that he could be with his family.
Eamonn, who usually presents ‘This Morning’ on Fridays alongside wife Ruth Langsford, joined Phillip’s regular co-host Holly Willoughby in place of him.
Explaining his absence at the top of the show, Holly said: "Sadly Phillip can't be here this morning as his brother has been taken ill suddenly."
"We wish him lots of love, and we are all thinking of you," she added.
Eamonn then joked: "How lucky are you that I was available?"
It is currently unknown what has caused Tim’s illness, but he does suffer from Type 1 diabetes.
Phillip, who is seven years older than his brother, regularly raises awareness of the condition, and has spoken about Tim’s condition in the past.
In an interview with Diabetes Advice last year, he said: “My brother was first to be diagnosed and he had an unquenchable thirst for fizzy drink, which was very unlike him.
“That continued for a few days, he was acting completely out of character. So we took him to the doctors and he was very quickly diagnosed. Then six months later my mum was diagnosed in the same way."
He added: “My brother was very young at the time of diagnosis, probably in his late teens. He had always been very healthy and active. He is also seven years younger than me so it was a shock, as far as we were aware there was no history of the disorder in the family.”
'This Morning' airs weekdays at 10.30am on ITV.