The effects on human hair growth of 7′-phloroeckol (1-(3′,5′-dihydroxyphenoxy)-7-(2″,4″,6-trihydroxyphenoxy)-2,4,9-trihydroxydibenzo-1,4-dioxin) isolated from E. cava (Ecklonia cava) have been studied in cell systems. The cell-proliferation and anti-apoptotic effects on human human hair follicle dermal papilla cells (HFDPC) and human keratinocytes (human epidermal keratinocytes: HaCaT) were investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and western blot. The 7′-phloroeckol significantly increased HFDPC and HaCaT proliferation. With HFDPC and HaCaT, the amount of PI3K and phosphorylated AKT protein expression increased in a way which was dependent on the extent of 7′-phloroeckol treatment. Also, the levels of MEK½, phosphorylated ERK and c-Fos proteins, which are associated with cell proliferation, increased in a way which was dependent on the extent of 7′-phloroeckol treatment. Meanwhile, apoptosis was inhibited as there was an increase in the Bcl-2/Bax ratio which is associated with apoptosis, and there was a significant reduction in p53 and also caspase-3 and caspase-9. These results indicate that 7′-phloroeckol can promote human hair growth by inhibiting apoptosis and stimulating HFDPC and HaCaT proliferation.