Green light therapy works on the upper layers of the epidermis (0.5 mm) where human epidermal melanocytes (HEMs) reside. These cells are responsible for melanin production, but when exposed to green light, the activity of a key enzyme in the synthesis pathway, tyrosinase, is moderated. By downregulating tyrosinase activity, green light therapy can hinder the excessive production of melanin, thereby reducing the accumulation of pigment in hyperpigmented areas. Green light has also been shown to break down melanin clusters within the skin, thus reducing the appearance of hyperpigmentation further, which can contribute to the appearance of dull skin.

Green light has also been found to promote cellular turnover and regeneration. Stimulating the skin cells helps shed the hyperpigmented layers and promotes the growth of new, healthier skin cells. It has also been found to promote angiogenesis - the formation of new blood vessels. These processes gradually lead to a more even complexion and the appearance of visibly brighter, more radiant skin.