In one of the photos, the future King of England, Prince George, examines a raised flowerbed with his finger, while looking smart in a signature polo shirt.
Another beautiful pic shows Princess Charlotte holding a pot plant upside down, while suitably clad in a blue skivvy, tartan skirt and Wellington boots.
A follow-up pic shows a curious Louis clutching on to a blue bucket as he crouches down and examines some sand intently.
William, who is seemingly following in his father’s sustainable footsteps, recently admitted he has become more concerned about the future of the environment.
“I’ve always loved nature… but fatherhood has given me a new sense of purpose,” William says in a first-look promo for the ITV documentary.
“Now I’ve got George, Charlotte and now Louis in my life, your outlook on life does change. You want to hand over the wildlife in a much better condition,” he added.
The documentary, which was filmed over the last few years, follows the prince’s travels as he visits countries such as Tanzania and Pakistan, where he identified the effects of climate change.
Later in the film, William mentions how the devastating impact of the coronavirus pandemic made it possible for people to “take stock” of what really matters in the world.
"Someone has to put their head above the parapet and say, I care about this… to have the belief that if we all work together, we can make a difference,” he said.