In support of 2022 winners Kalush Orchestra's opening performance, the clip of Kate, 41, recorded at Windsor Castle, features her wearing a blue Jenny Packham dress.
While the royal generally prefers to cover up in coat dresses, the one-shoulder gown belonging to the late Queen was chosen to match one of the colours of the Ukrainian flag in solidarity.
Also occasionally baring more in warmer climates, her sculpted arms last made an appearance when she arrived in Trench Town in Jamaica with Prince William on day four of their Caribbean in March last year, wearing a sleeveless dress as her third outfit of the day.
During their visit to the birthplace of reggae music, Kate stood out in an altered Willow Hilson Vintage dress.
While the 1950s stripped coral and turquoise dress previously sported spaghetti straps, the bodice appeared to have been amended to create thicker straps for the royal.
So, prompted by Kate showing her toned arms once again, here we delve into her workout regime.
When hosting a reception for the England Wheelchair Rugby League team at Hampton Court Palace in January, one of the athletes asked the royal if she goes to the gym.
"It's running around after the children – I do it all, whenever I can squeeze in exercise I do, even jumping on the trampoline with my children before school," she replied.
And when she's not chasing around after the little ones, Prince George, nine, Princess Charlotte, eight, and Prince Louis, five, she is in fact a well-known fan of the more conventional method of cardio. Previously appearing on House of Rugby, Mike Tindall was asked which royals he'd like on his rugby team, to which he said, "I've got the [then] Duchess of Cambridge on one wing because she loves running, she can run all day. Engine!"
It seems her sporty nature runs in the family. "Kate is an exercise junkie. Pippa and Kate take their toned physiques extremely seriously. And mother Carole, in her 60s, is in extremely good shape," a royal insider previously told the Daily Mail.
The source revealed Kate's secret is the plank. "It tightens her muscles," they said. "There are three elements, the basic plank, the side plank and the prone sky dive, all of which are positions Kate can hold for 45 seconds or longer and repeat at least 10 times each."
Watch: The Coronation weekend behind the scenes with the Prince and Princess of Wales
Kate was an advocate for CrossFit in its earlier days, which involves a combination of resistance training, weights, running and squats, and can improve health, performance or aid weight loss. The insider said she had reached "almost army fitness level" – all without a personal trainer.
She also reportedly has had a membership at the Harbour Club in Chelsea, a luxurious gym space in West London, where her mother-in-law, Princess Diana, went, as well as access to one conveniently in Kensington Palace.
Away from the gym, Kate has a keen interest in tennis, as a regular at Wimbledon and a patron of the Lawn Tennis Association. She's even played on the court with US Open champion Emma Raducanu, the first British woman to win a Grand Slam singles title since the 1977 Wimbledon Championships.
Raducanu commented that Kate's "forehand is incredible" and that she was "very, very impressed", to ITV News reporters after the match in September 2021.
The Princess of Wales is able to practise on her own court at Anmer Hall, her country house in Norfolk.
In terms of overall fitness, it's thought Kate used the so-called Louise Parker method to increase her strength after giving birth.
The Four Pillars of the method, according to the company's website, are 'eat beautifully', 'move intelligently' 'think successfully' and 'live well'.
This includes a range of balanced food tailored to you with 'no shakes, no supplements, no points', moving every day with exercises you enjoy, rewiring your behaviour patterns to 'support your motivation' and incorporating lifestyle hacks that 'save time, simplify your lifestyle, and create space for you to prioritise your wellbeing'.
Other activities Kate has been known to enjoy include yoga, walking, skiing, skipping, indoor rowing and intense interval training, with her Swiss gym ball once a favourite to maintain toned abs.
The Prince and Princess of Wales even made their public debut as a couple on a ski trip in Switzerland in 2004.