The former Destiny's Child star, who sits on the panel with Tulisa Contostavlos, Gary Barlow, and Louis Walsh, walked out after Twisted were booted off the show.
But she then spent nearly half an hour convincing group member Chrissie Pitt to audition on her own.
According to British newspaper The Sun, Rowland, 30, told the contestant: 'What are you doing with these doo-wop singers? You don't need them, you're a stand-alone singer. You have such a good, powerful and melodic voice.'
But Chrissie was very upset about abandoning Twisted to sing alone.
An insider added: 'Chrissie was crying about leaving the other girls behind but Kelly persuaded her to audition by herself.
'Chrissie's so grateful to Kelly. Her former bandmates are still finding it hard to support her but she hopes they'll come around.'
Pitt went on to progress in the singing competition after auditioning on her own.