On Friday, summer hosts Andi Peters and Rochelle Humes confirmed that the television presenter — who is now The Morning’s head presenter — is returning on Monday.
Willoughby, 42, has been on her usual summer break from the show for the past few weeks, enjoying a vacation with her television executive husband Dan Baldwin and their three children.
Peters and Humes confirmed Willoughby will be joined by Alison Hammond for hosting duties.
It is not yet clear whether Hammond — who is the new co-host of The Great British Bake Off — will join Willoughby as permanent co-host.
Willoughby is expected to lead the show Monday to Thursday with Hamond and Dermot O’Leary predicted to continue on their usual Friday slot.
Earlier this year, Phillip Schofield departed his long-time This Morning co-presenting role after admitting to an affair with a younger male colleague.
Schofield, 61, resigned from ITV and was dropped by his talent agency YMU in May after admitting to the “unwise but not illegal” relationship.
Holly Willoughby had hosted This Morning alongside Schofield from 2009 onwards.
Despite the scandal, This Morning has been nominated for best daytime show at the National Television Awards — which take place next week.
Schofield and Willoughby had been longlisted for the best TV presenter prize, alongside fellow This Morning hosts Hammond, O’Leary, Rylan Clark and Martin Lewis, but only Hammond and Lewis made the cut on the shortlist.
Willoughby made a brief return to This Morning last month to promote her cameo on ITV drama Midsomer Murders, which screened on Sunday.
Teasing her role, Willoughby shared some behind-the-scenes footage, which airs on Friday’s This Morning, on her Instagram a day early and said that being on the series had been a “dream come true”.
She captioned the video: “Thank you to the whole team at Midsomer Murders for making me so welcome and really looking after me… I loved every second.
“Tomorrow there is a behind the scenes look at what we got up to on This Morning and then Sunday 8pm the episode, The Witches of Angels Rise, broadcasts on ITV.”