Microplastics (MPs) are a significant environmental concern due to their persistence and potential interactions with other contaminants. The interaction of MPs with AgNP, for example, could pose additional threats to organisms. Here, we assessed the influence of polystyrene microplastics (PS-MPs) on the bioaccumulation processes (uptake, elimination, and dietary assimilation) of silver (Ag) in the filter-feeding zooplankton Daphnia magna, using environmentally relevant concentrations of Ag. Results show that the presence of PS-MPs increased the influx rate (i.e., waterborne uptake) of Ag into D. magna by eightfold compared to that from AgNP alone. In addition, the presence of PS-MPs altered Ag elimination kinetics in Daphnia magna, resulting in faster and more complete depuration, with 98% eliminated after 5 days compared to 66% in their absence. The presence of PS-MPs reduced the algal food-ingestion rate in D. magna, an effect that was independent of Ag concentration. Modeling Ag concentrations at steady state using a biodynamic model showed that, when PS-MP are present, the primary pathway for Ag bioaccumulation in D. magna shifts, making waterborne exposure more dominant than dietborne exposure. These findings provide critical insights for assessing the ecological risks of metals to zooplankton. They also highlight that for filter-feeding organisms such as D. magna, particles such as PS-MPs can act as Trojan horses for contaminants like AgNP. Additionally, these results underscore the complexity of Ag bioaccumulation when microplastics and nanoparticles interact.