William met the beloved naturalist and filmmaker on Tuesday before attending a private screening of the broadcaster's new film, Ocean With David Attenborough, at the Royal Festival Hall in London.
"As he turns 99 today, in his new film, Attenborough has once again reminded us of the need to protect natural habitats - this time those beneath the ocean," the prince posted on social media on Thursday.
"He has dedicated his life to ensuring we understand the realities of what mankind is doing to the planet."
Attenborough has been on our TV screens for more than seven decades presenting programs such as Planet Earth and The Blue Planet.
Mike Gunton, creative director at BBC Studios Natural History Unit, told the PA news agency: "Each generation has its own kind of personal legacy from him, and ... that's remarkable.
"But also, there's a broader, I suppose, global legacy, which I think is that he has shown us wonders, he's helped us understand wonders, and he's encouraged us to protect these wonders."
Gunton began working with the broadcaster aged 29, said it had been "a life-defining experience" for him.
"Every program I have made with him has been a remarkable experience which the audience have always found completely memorable and worthwhile and that's a joy for anybody, to make things that are remembered, you know, they're historic, they're part of human history," Gunton said.
David Frederick Attenborough was born in London in 1926, the son of a principal of Leicester University College.
Before joining the BBC in 1952, he studied geology at the University of Cambridge and served two years in the Royal Navy.
He made his reputation with the groundbreaking Zoo Quest series, which he hosted for 10 years on the BBC.
In 1965 he became controller of BBC2, overseeing the advent of colour TV, and he later became BBC director of programming.
Ultimately, however, life as a broadcast executive did not appeal and he returned with relief to his early passions, program-making and filming the wildlife that fascinated him so much.
His famous whispering voice captured the imaginations around the world in 1979 when he was seen mingling and bonding with a family of gorillas in Life On Earth and its sequel The Living Planet in 1984.
He was knighted by the late Queen Elizabeth II the following year.
The TV presenter has two children, Susan and Robert, with his late wife Jane whom he married in 1950.
In recent years, Attenborough has presented shows including Dynasties, Prehistoric Planet and Planet Earth III.
In celebration of his 99th birthday, a new documentary about the health of the ocean will air in cinemas from Thursday.
It comes after the King and Attenborough attended the premiere of Ocean With David Attenborough in London on Tuesday.
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