In a reprisal of her Commonwealth Games opening ceremony performance, Benedetti played a rendition of the Bonnie Banks of Loch Lomond on the steps of the Royal Concert Hall in Buchanan Street.
She was backed by the Big Noise Orchestra during her performance at Celtic Park on Wednesday.
Benedetti, who also appeared as part of a flashmob at the Kelvingrove Museum earlier today, has hinted that she had something special planned for the city yesterday, tweeting: "Rehearsals for our top secret project with @NickyBenedetti - keep your eyes peeled for us tomorrow #Glasgow!"
Her inpromptu performance also attracted the attention of Masterchef winner Ping Coombes, who was giving a Malaysian cookery demonstration in Buchanan Street.
The 2014 Masterchef champion tweeted: "Just seen Nicola Benedetti performing on Buchanan St next to our truck! Awesome!!"