Holly, 35, was attempting to read the auto-cue and sit down on the sofa at the same time, but it was clearly too much for the presenter to handle so early in the morning as she ended up making her way onto her co-host's lap.
Not one to keep the mishap on the down low, Holly squealed and burst out laughing, as she attempted to explain what had happened.
Phillip quipped: "Let me tell you what happened there," as the pair both struggled to get their giggles under control.
Holly then insisted: "I knew the sofa was there," before she added: "I sat down on his lap!"
Holly Willoughby accidentally sat on Phillip Schofield's knee on today's This Morning
Pair struggled to control their laughter
I sat down on his lap!
The much-loved duo then cut to Rylan Clark-Neal who asked what was happening, before he said: "I bet you sat on his lap," with a cheeky smile on his face.
The gaffe came shortly after Phillip and Holly spoke to Amir Khan and his wife Faryl Makhdoom about the boxer's recently leaked sex tape and their family feud.
Holly was the first person to bring the sex tape up, but Phillip then went on to quiz the Bolton-born star on whether or not it was a family member that actually released the footage online; given the recent spat.
This Morning: The funniest moments
Mon, December 12, 2016
This Morning: Laughter, tears and nudity, the most outrageous moments from the ITV show.
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This Morning was thrown into chaos as Holly Willoughby and Gino D'Acampo took on the Christmas cocktail challenge
Holly was attempting to read the auto-cue and find the sofa
Holly and Phillip spoke to Amir Khan and his wife Faryal Makhdoom on today's This Morning
Amir explained: "It was something that happened a long, long time ago this was well before my marriage. All the good things I do, the charity work, it's upset me more than anything and it puts me in a difficult position. I was very young.
"I believe someone's done it out of revenge, I feel like someone's done it because of the family [feud]. Whoever did it probably thought this was the best time to do it."
This Morning airs weekdays at 10.30am on ITV.