The brunette beauty had to leave the studio for a brief time so she could be sewn back into her pale dress after the zip split open.
Upon her return, the 44-year-old told her co-hosts and ITV1 viewers: "I think no-one would have noticed - it's almost exactly the same dress."
Explaining what happened, she continued: "My dress broke… during the news bulletin, the back of it completely split open.
"Behind the scenes the lovely wardrobe mistress was trying to sew me into the dress. I think physics and my sheer width proved a bit of an obstacle."
Kate, 47, reassured viewers in Susanna's absence, before sharing a light-hearted joke at her, and John's, expense.
"I think we should explain that Susanna has just nipped out the studio after a slight wardrobe malfunction. All will be sorted out, although it has warmed John up this morning.
"He's very pleased about it. It was all marvellous for a moment there for you," before adding: "I tried to help but there was little I could do."
John, 69, later quipped to the pair: "One of the advantages to this job that they don't put in the job description."
