The present invention relates to a cosmetic composition for coating keratinous fibres of the emulsion type, comprising: —an aqueous phase, —at least one wax, and —an emulsifying system comprising: i) at least one anionic surfactant in the salt form, ii) at least one cationic counterion, and iii) at least one basic amino acid, in which the total content of basic amino acid(s) and the total content of anionic surfactant(s) in the salt form are such that the ratio by weight of the basic amino acid(s) to the anionic surfactant(s) in the salt form is greater than or equal to 0.05. The present invention also relates to a method for coating keratinous fibres.