He quit ITV and said the relationship had been "unwise but not illegal".
ITV said it had investigated in 2020 but found no evidence of the affair beyond "rumour".
On Sunday, lawyers representing Schofield confirmed to the BBC that the pair had met when the younger colleague was a 15-year-old boy.
Schofield's This Morning co-host, Holly Willoughby, said she was "very hurt" to discover Schofield had lied to her about his affair.
ITV bosses are facing questions about whether the show can survive the scandal.
Dr Ranj Singh criticised the "toxic" culture at the programme and said the issues "go far beyond" Schofield.
ITV responded by saying it was sorry to read Dr Ranj's post and that an external review found no evidence of bullying or discrimination.
The show will return as normal on Monday.
The story describes a relationship between a man and a younger male colleague at This Morning, a British television program.
The man stated that the relationship was "unwise, but not illegal" when he was a teenager.
In a later statement, he admitted to having a consensual on-off relationship with the male colleague while still married to his wife.
He apologized for being unfaithful and lying about the relationship to various people.
LONDON DAILY ARCHIVE
TV Personality Admits to Affair with Teen Colleague, Quits ITV Amid Scandal
On Friday, Phillip Schofield confirmed that he had a relationship with an employee while married and lied repeatedly to hide it.
28 May 2023 · 21:11 UTC
