The two professional dancers clearly had moves even back then, as they posed as if they were just about to start a new routine!
In the black-and-white picture, Joanne, now 36, wore a uniform of a V-neck sweater over a skirt and pleated skirt.
Her older brother, now 37, wore smart trousers with a shirt and tie, as well as a blazer that appeared to be several sizes too big.
Kevin captioned the rare image from his childhood: "Oh yeah I was that kid in school... @realjoanneclifton."
WATCH: Stacey Dooley reveals how she and Kevin Clifton pass the time at home
Kevin's other followers agreed with the documentary maker, with one joking: "@sjdooley I bet that blazer is too big even now," and another adding: "Growing room."
Other fans simply welcomed the behind-the-scenes glimpse into the star's early days as a dancer, commenting: "Getting strong Billy Elliot vibes from this pic…"
Kevin and Joanne were taught to dance by their parents
"You look very cute in that picture [heart emoji]," and: "Love this! Your destiny was set in motion @realjoanneclifton @keviclifton xx"
Like Kevin, Joanne won Strictly back in 2016, lifting the iconic glitterball trophy alongside her celebrity partner Ore Oduba.
Joanne, who had been a professional on the show since 2014, left after that series, while Kevin, who joined the BBC show in 2013, announced his departure earlier this year.
The talented pair were both taught by their parents Keith and Judy, who are former world champion dancers, and Kevin and Joanne competed together nationally and internationally as children.
The siblings are still very close and after Kevin and Stacey won Strictly, his sister shared how proud she was of him.
The following day, Joanne posted a photo on Instagram of herself and Ore with Kevin and Stacey, which she captioned: "Still tearing up this morning seeing this picture…
"What a year he's had... I can't even tell you just how much last night meant for him."
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