Self-adherent composite reinforcement (R-2) adhering, by curing, to a diene rubber matrix, which can be used as reinforcing element for a tyre, comprising: one or more reinforcing thread(s) (20), for example a carbon steel cord,a first layer (21) of a thermoplastic polymer, the glass transition temperature of which is positive, for example a nylon-6,6 polyamide, covering, individually, said thread, each thread, or collectively several threads,and a second layer (22) comprising a functionalized diene elastomer bearing functional groups chosen from epoxide, carboxyl and acid anhydride or ester groups, for example an epoxidized natural rubber, covering the first layer (21). Process for manufacturing such a composite reinforcement,and rubber article or semi-finished product, especially a tyre, incorporating such a composite reinforcement.