Alongside a clip from Jurassic Park of Jeff Goldblum's character being chased by a dinosaur, Smith commented on seeing the star at meat-free chain Veggie Grill.
He wrote: "Being Vegan has finally paid off: I just saw Jeff Goldblum at my local @VeggieGrill! Makes sense that he's plant-based, considering he was almost eaten that one time…"
In addition to crediting the lifestyle for his celebrity run-in, Smith has praised veganism for improving his health - discussing the topic in interviews and online.
The star reports that he's 51 pounds down, and has restored his blood pressure to healthy levels as a result of his plant-based diet.
He now regularly shares aspects of his new lifestyle online, with one of his more recent posts showing him eating a vegan burger on National Burger Day.
Smith was inspired to go vegan by his daughter Harley Quinn - who he has publicly thanked for her influence - and by his need to lose weight after a life-threatening heart attack he suffered early this year.
?The star explained on the Joe Rogan podcast that the heart attack - which was the result of complete artery blockage - was caused in part by an unhealthy diet.