The athlete revealed he'd adopted a plant-based diet in September 2017 on Snapchat after watching documentary What the Health.
Since then, he's become increasingly outspoken about the ethical, environmental, and health benefits of dropping animal products.
Hamilton made two Instagram posts yesterday focusing on animals, and how they are often made to suffer by humans. "Animals possess values of which very few humans do," he wrote on one. "We turn a blind eye to the pain and torture we put animals through.
"Every bit of meat, chicken, or fish you eat, every bit of leather or fur you wear, has come from an animal that has been tortured, pulled away from their families and brutally killed.
"We all have choices to make and if you are ok with it, then that's you, but I choose to love, to be conscious of what I'm supporting and I refuse to support the companies that buy from those companies killing and torturing animals."
'The price of bacon'
The star then shared another post, an image of a mother pig discarded in a bin with her piglets. The picture had writing on it saying: "A mother and her babies tossed away like trash. Their rights were never considered, their lives were never theirs to live. This is the price of bacon."
Hamilton added his own caption saying: "We all have a voice, I have this platform so to not use it correctly would be wrong of me. Nobody is perfect, I certainly am not, but this is actually happening every day to so many animals worldwide.
"This is why I decided to go to a vegan plant-based diet, [it 's] been over a year now. Yes it's hard, nothing's ever easy but I've felt the best I've ever felt for the past year."