Short answer: we do not have verified evidence that psilocybin slows human aging or extends lifespan. Current findings are preliminary and mostly come from cell work, animal studies, and small exploratory observations.
Some laboratory and mouse studies suggest psilocybin or its metabolite psilocine may influence processes linked to aging, such as oxidative stress, inflammation, and telomere maintenance. These signals are not proof for humans, and self-experiments cannot establish causation or generalize outcomes.
Because mental and physical health are connected, improvements in mood, stress, or sleep might indirectly support healthier aging, but this remains unproven until tested in controlled trials.
To confirm any longevity effect, we need rigorous human studies that track aging biomarkers and long term safety and outcomes. Until then, psilocybin should not be considered an anti-aging therapy. For background on proposed mechanisms like telomere protection, see this overview.
Bottom line: promising signals, not proof.