Face of Nation : The R&B star will be among acts including George Ezra and Lewis Capaldi performing on the main stage at Glasgow Green on Sunday 14 July.
Glynne announced on 26 June that she would not be able to perform because of vocal cord damage.
It came after Snow Patrol also pulled out of their Sunday night slot.
Festival director Geoff Ellis comments: “We are pleased to reveal that the incredible Emeli Sande will join the Sunday bill for TRNSMT.
“She is an outstanding live performer and we’re looking forward to seeing her back on stage – perhaps with a preview of her forthcoming album Real Life.”
TRNSMT will be staged over three nights from Friday to Sunday.
