The sweet picture was taken by keen amateur photographer Kate at Kensington Palace on Wednesday before Louis attended his first day at nursery school.
Louis is following in his older sister Princess Charlotte’s footsteps by attending Willcocks Nursery School.
The cute royal, who is sitting on a red bike, does not appear to have any first day nerves as he grins for the camera.
Louis looks smart in blue shorts teamed with a shirt, jumper, matching socks and trainers in the same shade.
Prince Louis looks very grown up in a new picture released as the young royal turns three
The Duke and Duchess of Cambridge shared an adorable snap of Louis to mark his birthday
His dark blonde hair is neatly styled and he is wearing a backpack.
Kate regularly releases images of her children to mark major milestones like birthdays.
Prince Louis Arthur Charles was born at 11.01am on April 23 2018 – St George’s Day – weighing 8lb 7oz.
Kate and William showed him off to the world on the steps of the Lindo Wing of St Mary’s Hospital in Paddington, London, after his arrival.
Louis is a younger sibling of George and Charlotte
Louis, who is fifth in line to the throne, is a great-grandchild of the Queen.
He is a younger sibling of Prince George, seven, and five-year-old Charlotte.
The young royal is not often seen in public.
Kate and William showed Louis off to the world on the steps of the Lindo Wing after his arrival
Louis’ most prominent outing during the past 12 months was when he joined his parents and siblings at a special pantomime performance at London’s Palladium Theatre last December
His most prominent outing during the past 12 months was when he joined his parents and siblings at a special pantomime performance at London’s Palladium Theatre last December.
His birthday comes as royal mourning for Prince Philip ends for the Royal Family on Friday.
The royals will resume their official roles in full after observing the two-week period of mourning for the Duke of Edinburgh, who died peacefully aged 99 at Windsor Castle on April 9.
Louis’ birthday also comes after the Queen turned 95 on Wednesday.
The monarch marked the day privately in Windsor following the death of her beloved husband.
Philip’s death came just two months before his 100th birthday, which was due to be the focus of royal celebrations this year, while the Queen’s 95th was to be more low-key.
Source: EXPRESS CO UK