The presenter recently returned to the show after taking pre-planned leave around his brother’s sex abuse trial at Exeter Crown Court last month.
The Sun previously reported the absence had contributed to a “cooling” of their friendship.
But in a statement, Schofield, 61, told the paper: “As I have said before, Holly is my rock. We’re the best of friends – as always, she is an incredible support on screen, behind the scenes and on the phone.
“Holly has always been there for me, through thick and thin. And I’ve been there for her.
“The last few weeks haven’t been easy for either of us.”
In April his younger brother Timothy Schofield, 54, was convicted of 11 sexual offences involving a child between October 2016 and October 2019, including two of sexual activity with a child.
Willoughby, 42, was also ill and took time off This Morning.
Schofield added: “My family went through a real ordeal, and Holly’s support throughout meant the world to me – as did the support of my bosses at ITV, my editor Martin Frizell and the whole This Morning family, including our amazing viewers.
“And of course Holly has herself been ill with shingles.
“Whatever happens, we still have each other to count on.”
Schofield has been a regular presenter on This Morning since 2002 alongside hosts including Fern Britton and Amanda Holden.
Schofield and Willoughby, who also present ITV’s Dancing On Ice together, have become firm favourites with the public.
In October Schofield thanked viewers after This Morning took home the daytime prize at the National Television Awards, saying: “This means so much to us every year, especially this year.”
It came after the co-hosts had faced criticism over claims they skipped the queue for the Queen’s lying in state.
