He captured the world’s attention last year with a star turn at the late Queen's Platinum Jubilee celebrations, displaying his lively sense of fun.
Now aged five, Prince Louis is all grown up but still full of fun as these adorable new photographs show.
The little Prince is seen sitting in a wheelbarrow of garden weeds and being pushed by his doting mother the Princess of Wales, grinning at something beyond the camera.
In his blue shorts and checked shirt, under a bright blue fair isle sweater, he is dressed for outdoor play in the garden of his family's home at Windsor.
The images were taken by Millie Pilkington in the grounds of the family's Windsor home last week.
Millie has a longstanding relationship with the Prince and Princess, having been the private photographer at their 2011 wedding and she is known for her stunning portraits of babies and children
Fourth-in-line to the throne Prince Louis is set to appear alongside his parents and older siblings Prince George, nine, and Princess Charlotte, nearly eight, in the Coronation Procession from Westminster Abbey to Buckingham Palace on May 6, following the crowning of his grandfather the King.
"He's so grown up all of a sudden, and has a big year ahead," a family friend tells HELLO!
Louis already has one major public carriage ride under his belt, having made his debut in the Trooping the Colour procession to mark the late Queen's milestone last June.
DISCOVER: Prince William makes the sweetest comment about Princess Kate during joint outing
William and Kate's youngest child has been spending more time in the spotlight over the past year, joining the royal family for the Easter Sunday service at St George's Chapel at Windsor earlier this month and waving to the crowds on Christmas Day as the party walked back from church to Sandringham House.
But he is perhaps best known for sparking a string of hilarious memes after appearing on the Buckingham Palace balcony with his hands over his ears as he stood alongside his late great-grandmother Queen Elizabeth to watch the military flypast last June.
He went on to delight royal watchers with his antics, poking his tongue out and thumbing his nose at mum Kate, planting a kiss on her cheek, pointing his fingers in the air and later bouncing up and down on the knee of his Grandpa Wales – now King Charles III.
He was even teased by Mike Tindall, who jokingly pointed at his own eyes as if warning the little boy he was keeping an eye on him. Take a look back at Louis' best moments from the Platinum Jubilee in the clip below...
The Prince and Princess seemed to take his high spirits in their stride, later commenting in a social media post: "We all had an incredible time…especially Louis.." and added a side-eye emoji.
Prince Louis Arthur Charles was born at 11.01am on April 23, 2018, meeting his big brother and sister for the first time just hours later.
He spent a year at Willcocks Nursery in Kensington while the family were still based at Apartment 1a at Kensington Palace.
Now aged five, Louis is enjoying an idyllic childhood at Adelaide Cottage in Windsor, where the Wales family now lives while all three children attend Lambrook School.
MUST-READ: Prince Louis' biggest milestones ahead of 5th birthday
Despite speculation that they plan to move into the much grander Royal Lodge when it is vacated by the Duke of York, the Prince and Princess and their children are very comfortable in the four-bedroom property, which boasts expansive gardens in the heart of Windsor Home Park.
A friend tells HELLO!: "They are so happy there, it’s just them and the kids and they can run free outside in total privacy.
"It feels very much like a home to them and they are really settled now. It's just the five of them and they love it."
Louis is now two-thirds of the way through his first year at school, having joined his older siblings at Lambrook in September.
The school offers outstanding teaching as well as after school activities including tennis, ballet and cooking, and the energetic little Prince will be making the most of the 52 acres of grounds.
He has clearly inherited his parents' sporty sides, with Kate revealing last year how his favourite sport is rugby.
Speaking at a reception for England's World Cup-winning wheelchair rugby league squad in January, the Princess said of her brood: "They all love sport and Louis is mad about rugby. They’re at an age where they just love running around.
"They’re all enjoying it, Louis is kamikaze, we're worrying about when he gets older, he'll be in the middle of everything."
On a visit to Wales last month Kate added that her outdoorsy son loves to get outside as soon as he comes home from school, with the trampoline in the garden a favourite. She said: "Louis comes homes and says, 'I need to get my energy out!'"
No doubt the Princess took the opportunity to bake her youngest son a special cake to mark his big day on April 23, honouring the tradition she has kept for all of her children.
Speaking to chef Mary Berry in 2019, she said: "I love making the cake. It's become a bit of a tradition that I stay up 'til midnight with ridiculous amounts of cake mix and icing and I make far too much. But I love it."