Parrs Wood High School were chosen to perform at the charity concert after a video of them singing an Ariana Grande song went viral just days after the harrowing Manchester bombing last week.
The choir appeared on This Morning to give hosts Eamonn Holmes and Ruth Langsford a taste of what the One Love Manchester concert attendees can expect.
As they performed Ariana's ballad, My Everything, viewers took to Twitter to praise the "beautiful" choir.
One posted: "The voices of the school choir is outstanding. Well done to them all and wishing them a great performance on Sunday #ThisMorning #Manchester." (sic)
Parrs Wood High School were chosen to perform at One Love Manchester
This Morning viewers were in tears over their performance
Another added: "The choir is giving me goosebumps & bringing tears to my eyes as I hug my 3 month old @thismorning #OneLoveManchester #ThisMorning."
A third tweeted: "The choir on #ThisMorning is making me cry all over again."
The group will perform on Sunday alongside the world's biggest pop stars including Justin Bieber, Katy Perry and Take That.
The group will perform alongside the world's biggest pop stars including Coldplay and Katy Perry This Morning: Then and Now Mon, May 8, 2017
This Morning presenters then and now: From Holly and Phil to Ruth and Eamonn.
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Holly Willoughby pictured in 2004 and now
One Love Manchester will be in aid of those caught up in the horrific terror attack that saw 22 people killed and many more injured.
The concert will be shown on BBC One this Sunday between 6.55pm and 10pm as well as being broadcast on BBC Radio and Capital Radio Networks.