The star, who often uses his platform to speak out about animal-rights, shared a video of him holding a How To Go Vegan book on Instagram.
'Hovering on the edge'
"Starting on the first of January I, this coming year I will be doing VEGANUARY. Which means I will eat only vegan food for that month," May said to his 2.1 million followers.
"If any of you folks out there are hovering on the edge out there and want to join me too, I'd be delighted. We can mutually support each other! I figured this book is a good place to start.
"My reasons? 1) to lessen the suffering of animals. 2) To lessen the load on our groaning planet. 3) for my health. And... as an animal campaigner, it has been bothering me for a while that I still eat animal-derived food, that has caused indignity and pain to a non-human animal."
The celebrity said when Veganuary comes to end, he will 'take a view' on whether to continue being plant-based.
Veganuary, the world's biggest month-long pledge to adopt a vegan lifestyle, aims to receive 350,000 sign-ups for next year.
Last January, a record-breaking 250,310 people registered, as a plethora of top celebrities backed the incentive.
"WOW!! We've already hit the 200,000 sign-ups mark with a few days to go before January!" Veganuary wrote on Twitter.
You can sign up or learn more about Veganuary here