The Oscar-nominated actress joins two sitcom stars on the red couch.
She'll appear alongside Eric McCormack and Debra Messing from Will and Grace to have the craic with the famous chat show host.
Comedian Rob Beckett and actress Keala Settle will also be part of the programme that'll air on BBC One from 10.35pm.
It's not Saoirse's first time chatting to Graham - here's a clip of her appearance on the show a whole five years ago!
Cover image via The Late Late Show/YouTube
