Wireless body area networks (WBANs) is now a well‐accepted technology that provides not only efficient and remote health‐care services but also targets the integration of future multimedia applications, in which high data rate is compulsory. UWB communication is one of the key solutions that afford such rates, and its extended version, multiband OFDM (MB‐OFDM) has recently shown its efficiency with WBANs. However, increasing the data rates may come at the expense of the data reliability which is a critical issue in biomedical applications. Cooperative diversity has proven its ability in offering such robustness to channel errors while avoiding to use multiple antennas. Indeed, a single antenna terminal is sufficient to achieve diversity benefits by sharing its physical resources with cooperating single antenna relays. Aiming at providing a viable compromise between the data rate and accuracy in low‐profile UWB body networks, to incorporate a decode‐and‐forward‐based cooperative architecture in MB‐OFDM system by resorting to opportunistic relaying approach is proposed, which retains only the best on‐body relay to forward the information to the destination, thereby significantly reducing the complexity.