Jo Whiley apologised to Fearne Cotton for "not supporting" her more during her time on BBC Radio 1.
The presenter, 44, took over the station's weekday mid-morning show from Whiley, who moved to weekends.
Whiley described how she was unaware of how difficult Cotton was finding the transition behind the scenes, as she faced criticism from listeners.
During an interview on her Dig It podcast with Zoe Ball, Whiley told Cotton: "I was oblivious, that was the worst thing. I guess I had moved on to my next thing, and I didn’t realise what you were going through.”
