The Osmonds legend thrilled fans when he spotted the I Dreamed a Dream singer in the Hydro audience and invited her to perform with him.
The pair belted out a rendition of This Is the Moment which they recorded together back in 2012.
In a video posted on social media, Osmond can be seen holding the Blackburn-born Britain’s Got Talent star’s hand as she smiles before he hugs her and hands over the microphone during the shock reunion.
A stunned Boyle, 62, can be seen finding her place in the song before belting out the chorus and singing in unison with Osmond.
Crowds begin to cheer at the “magic” moment before the song comes to an end and he hugs her again.
Osmond then can be seen thanking Boyle before kissing her on the head and asking for a member of the audience to help him back onto the stage.
The clip finishes with him telling the crowd, “That was a treat – thank you, Susan. I love that woman.”
Catherine Chisholm, who filmed the clip, posted to Facebook: “Magic night with Donny Osmond in Glasgow. And lovely seeing Susan Boyle again too.”
Linda McGregor added: “I was there last night and saw Susan, and she was fantastic.”
Jeanie Jaco said: “I love Donny so much.”
It follows Boyle’s triumphant comeback in the final of Britain’s Got Talent earlier this year.
She revealed that she had suffered a minor stroke in 2022 and had to relearn how to speak clearly again.
She underwent intensive vocal coaching so that she was able to sing again.
