The star, who went plant-based to improve his health after a recent heart attack, took to Instagram this week to share a picture of himself and Harley and celebrate his change in lifestyle.
He wrote: "She's been my role model for my plant-based lifestyle. Had no idea that having a kid would indirectly save my life, but she did."
This is not the first time Smith has thanked his daughter - a self-described 'friend to all animals' - for her influence on his lifestyle.
Smith took to Instagram in August to celebrate a 51-pound weight loss as a result of his change in diet.
In the caption, he wrote: "I also wanna thank my kid @harleyquinnsmith - the little vegan astronaut who explored this meatless/milkless galaxy ahead of me, leading by example."
In May, Smith told podcast hosts Jim Norton and Sam Roberts that the heart attack he had was caused by a 100 percent artery blockage.
He added that this type of attack - often called 'the widow maker' - has only a 20 percent survival rate.
Now, Smith reports not only weight loss, but that his blood pressure has been restored to healthy levels thanks to his change in diet.