Ageing is a complex, multifactorial biological process driven by a network of molecular and cellular mechanisms collectively known as the twelve hallmarks of ageing: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, disabled macro-autophagy, chronic Inflammation (Inflammageing) and dysbiosis. These interconnected hallmarks contribute to progressive physiological decline and increased susceptibility to chronic diseases. Greece’s rich botanical heritage offers a unique reservoir of natural compounds with demonstrated activity against these core mechanisms. This chapter explores the potential of Greek phytochemicals—including oleuropein, chlorogenic acid, α-terpineol, silymarin, crocin, and secoisolariciresinol diglucoside (SDG)—to modulate these ageing pathways. Through mechanistic insights from in vitro, in vivo, and emerging clinical studies, we highlight how these compounds stabilize DNA, protect telomeres, regulate nutrient-sensing pathways, promote proteostasis and mitochondrial integrity, reduce senescence and inflammation, and support stem cell function. Integrating traditional ethnopharmacological knowledge with modern geroscience, this chapter positions Greek natural compounds as multi-targeted, culturally relevant tools for delaying ageing and extending healthspan. By bridging phytochemistry, systems biology, and translational research, we propose evidence-based strategies for leveraging Greece’s phytodiversity in the development of holistic anti-ageing interventions.