Cowell, who will turn 60 this year, has already ditched meat, dairy, wheat, sugar and claims his new diet has made him more handsome - saying 'I was an eight [out of 10] and now I’ve gone to an 11'.
He says he will be giving up fish too to make his diet 100 percent plant-based.
Health and vegan diets
Cowell says he changed his eating habits after a major fall down some stairs in October 2017, which left him questioning his unhealthy lifestyle.
He revealed that while he used to love 'comfort foods' like jam tarts, hamburgers, and spaghetti Bolognese', he has found it surprisingly easy to change his diet, and this year he will 'go the whole way' when he ditches fish.
Changing his diet
"I cut out a lot of the stuff I shouldn't have been eating and that was primarily meat, dairy, wheat, sugar - those were the four main things," Cowell told The Sun. "It was way easier than you may think. Like, I used to have yogurt in the morning and I changed it to almond-milk yogurts. I have almond milk in my tea.
"I can eat certain fruits but not all fruits. You have to be careful because some fruit can have more sugar than a can of Coke. Once you get into a pattern I've found it quite enjoyable. It has helped me sleep and I wake up feeling less tired. I noticed a massive difference in how I felt in about a week.
"I have more energy and focus and it wasn't difficult. I don't like to use the word diet because that’s the reason I never went on a diet before - the word diet makes me miserable."
Simon Cowell - animal lover?
While Cowell appears to have changed his diet based on health factors, in the past, he has done advocacy work on behalf of animals, primarily dogs.
In October 2018, Cowell donated $32,640 to the Humane Society to help close down a South Korean dog meat farm - a move which impacted many animals positively.
"Simon's generous donation means the world to us," The Humane Society's UK Executive Director Claire Bass said at the time. "The dog farms prevent man's best friend from living under especially cruel circumstances, and instead, provide soft beds and loving arms for the first time in their lives."