The 21-year-old Australian recently teamed up with the heir to the British throne after he was was named a Global Ambassador for the Prince of Wales' Earthshot Prize.
"I think Prince William has been such an amazing person to work with, and there is such an incredible synergy between what he does and who he is and who we are," he told UsWeekly.
"It's all about conservation."
""I think it's wonderful that someone so influential - that has such a fantastic platform - is using that to really better our environment," he said.
"He is a true environmental hero, and so working with him has been a great privilege."
Irwin insists that everyone needs to "prioritise" the environment, saying William is "at the forefront" of that movement.
"We've definitely compared a lot of notes in the conservation space," he said.
"We need to prioritise taking care of our natural world. And he's really at the forefront of that.
"And plus, he's just a great guy. When you have a conversation with him, he's the most lovely, intelligent person to talk to and is just so easygoing, so much fun.
"And I love working with him. He's a really, really, really good guy."
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