Ronnie (Samantha Womack) is set to arrive back in Walford in autumn after spending two years in prison for stealing Kat's baby son Tommy.
Is steely Kat (Jessie Wallace) beginning to melt?
Kat Moon with Tommy
According to the Daily Star, she will accept Ronnie back on to the Square, believing that she has been through enough turmoil already.
However, an 'EastEnders' spokesperson has refused to confirm or deny the report.
Samantha Womack will reprise her role as Ronnie Mitchell
Ronnie isn't the only character returning to the BBC1 soap. On Thursday, it was confirmed Michael French will reprise his role as womaniser David Wicks.
And Barbara Windsor will reprise her role as Peggy Mitchell for one episode.
The news comes as viewing figures for 'EastEnders' fell below five million.
Executives on the show are said to be confident that the return of some familiar faces and big storylines - including Phil Mitchell being involved in a car crash - will win back viewers who have switched off - as well as attracting new ones.