The Do Ya Think I'm Sexy singer watched the chaotic match from the posh seats at Hampden Park with his family before venturing out into the city centre.
And he was happy to celebrate with fans after watching Celtic win 6-5 on penalties after 120 eventful minutes ended 3-3.
Stewart was all smiles and laughs as he got behind the mic and belted out his fan-favourite song Maggie May.
He got up on stage alongside John McLaughlin, the singer from Glasgow-based band Johnny Mac & The Faithful, and Scottish country star Kevin McGuire.
@kevinmcguireofficial Surreal moment!! 🤠🤯👊🏼 #rodstewart #maggiemay #glasgow #fyp
Rod Stewart wants to return to Las Vegas with a "big band" swing show. Get tickets today
Rod Stewart’s long-running Las Vegas residency The Colosseum at Caesars Palace will be coming to an end next summer. The Rock & Roll Hall of Fame singer’s “Rod Stewart – The Hits” show will wrap up with seven newly announced performances taking place July 24, 26, 27, and 31, and August 2, 3, and 7.
He told the Daily Star newspaper's Wired column: "When I go back to Vegas - and I'd like to - if the album's a big success, maybe I could do a swing show, big band stuff."
He added: "That two hours on stage is the most potent drug you can imagine. It's highly addictive.
"It's all the bloody in between time I don't like, sitting in hotel rooms. Although when I am sat around like that, I build my model railroad so that I'm not idle.
"It's something I'm working on for five or six hours a day. While all the banders are sitting around picking their noses, I'm occupied."
Tickets are available through StubHub where orders are 100% guaranteed through StubHub’s FanProtect program. StubHub is a secondary market ticketing platform, and prices may be higher or lower than face value, depending on demand.
Links to buy tickets
July 24 at Caesars Palace in Las Vegas, NV |
July 26 at Caesars Palace in Las Vegas, NV |
July 27 at Caesars Palace in Las Vegas, NV |
July 31 at Caesars Palace in Las Vegas, NV |
Aug. 2 at Caesars Palace in Las Vegas, NV |
Aug. 3 at Caesars Palace in Las Vegas, NV |
Aug. 7 at Caesars Palace in Las Vegas, NV |
Aug. 10 at The Venue at Thunder Valley Casino Resort in Lincoln, CA |