The chart star, who found fame through The X Factor, was a guest on the ITV programme and was promoting a forthcoming single when she crumpled to the floor, with her backing band rushing round and coming to her aid.
It is thought Ferguson, who will head out on tour in little over a fortnight, had fainted.
She told fans only yesterday that she was feeling unwell and suffering from a "bug", but was hoping to be well for her day of promotion.
Fans expressed their concern, with many posting messages on Twitter asking about her welfare.
Ferguson releases a new single All That I've Got on Monday, taken from her second album Freedom.
TV bosses did not screen the collapse when the show was repeated on the station's +1 catch-up channel, replacing it with a message which said: "Legally we're not allowed to show you what was on earlier."
Following the show, Ferguson said she was feeling better and said she slumped because she simply had "nothing left" after pushing herself to get through the track.
In a message posted online, she said: "I am feeling much better. Will rest today. So sorry to worry everybody. I fought through that song, but at the end had nothing left."
A spokeswoman for the show said: "Rebecca became unwell during her performance on the show today. She was seen by a nurse at the studios and is fine now."