Harris will join Mumford & Sons in special performances of her own hits 'The Road' and 'Orphan Girl' as well as the band's 'Awake My Soul' and 'The Cave'.
The concert was recently taped in Nashville and is to air on Thursday, September 27 at 9pm ET on CMT.
Crossroads brings together classic and contemporary artists to play new versions of their most well-known hits.
Steven Tyler and Carrie Underwood teamed for an episode at the Superbowl earlier this year and an earlier instalment paired The Pretenders and Faith Hill.
Keith Urban, Suglarland, Lucinda Williams, Dolly Parton, Kelly Clarkson and Sting have also appeared on CMT Crossroads.
Watch Mumford & Sons perform 'Awake My Soul' below: