Male pattern hair loss is a major cosmetic concern affecting both genders with a preference for men. Major causes of hair loss in genetically predisposed individuals include hormonal dysfunction, loss of extracellular matrix (ECM) proteins in the follicular bed, and localized microinflammation. Few options are yet available to correct the problem. For this purpose, a cosmetic active ingredient was developed by combining a Trifolium pratense flower extract and a biomimetic peptide and tested clinically for the prevention of hair loss. Thirty volunteers with recessing hair were recruited for this randomized, placebo-controlled study. Clinical efficacy, following daily topical application of the mixture to the scalp, was checked using TrichoScan™ for the measurement of human hair. Within 4 months of application, anagen hair increased at an average by +13%, telogen hair density decreased by -29%, and the anagen/telogen (A/T) ratio increased by +46% over baseline in the treated group. Results strongly differed from those of the placebo group (anagen, -2%; telogen, +23%; A/T ratio, -33%). Investigation of the potential mechanisms involved in the positive effects of the test product on hair growth pointed at inhibition of 5-α-reductase activity, reduction of inflammatory reactions, and stimulation of ECM protein synthesis in the vicinity of the hair follicle.