In this contribution a novel invasive weed optimization (IWO) based multi user detector (MUD) aided time-hopping ultra-wide band (TH-UWB) system has been investigated in the indoor channel model. In this approach, the IWO based MUD employs the output of the Rake receiver as its initial value to search for the best solution which results on a formulated optimization mechanism. By taking advantage of the heuristic values and the collective intelligence of IWO technique, the proposed detector offers almost the same bit error rate (BER) performance as the full-search-based optimum multi-user detector does, while greatly reducing the potentially computational complexity. The good behavior of the proposed approach is demonstrated by means of comparisons in terms of BER performance and implementation complexity with the classical Rake receiver and different multi-user receivers previously proposed in the literature of this subject. Simulation results have been provided to examine the evolutionary behavior and the detection performance of the proposed IWO based MUD in both the additive white Gaussian noise (AWGN) and the multi-path fading channel.