The 81-year-old took to the stage in a stunning, floor-length gown to perform one of Sir Bruce Forsyth‘s “favourite songs”.
She dazzled in the lace frock, which was adorned with pearls on the bust while she sported a slick of red lipstick.
But while Dame Shirley gave a stellar performance, viewers were left speechless over her youthful appearance.
Many took to Twitter to gush over her appearance and her faultless vocals.
“Dame Shirley Bassey does not age looks amazing #SirBruceACelebration,” one viewer shared.
Another added: “My goodness Bassey still incredible at 81 #SirBruceACelebration.”
A third continued: “Is Shirley Bassey really 81? Good grief. She looks amazing.”
“81, and she’s still got it! DAME SHIRLEY BASSEY, I am in awe! #sirbruceacelebration,” someone else shared.
A fifth wrote: “Dame Shirley, she’s still got it, at 81. Puts todays “singers” to shame #sirbruceacelebration.”
Meanwhile, Karen and Kevin Clifton surprised viewers when they performed a tribute together.
The Strictly Come Dancing couple took to the stage together with their fellow professional dancers to perform to a Frank Sinatra hit.
Kevin could be seen lifting up his wife and spinning her around, which sent fans into a frenzy.
“Aww so great to see @keviclifton & @karen_hauer back dancing on my TV! Love you guys! #SirBruceACelebration,” one viewer shared.
As another wrote: “Karen and Kevin dancing together again! #SirBruceACelebration #Strictly.”
Sir Bruce’s wife Lady Wilnelia later took to the stage to pay tribute to the late entertainer.
Sir Bruce: A Celebration is available to watch on the BBC iPlayer now.