A significant number of emerging pollutants resulting from point and diffuse pollution can be found in the aquatic environment. Pharmaceuticals, including antidepressants, are increasingly consumed across the world. Their good water solubility and resistance to biodegradation are major challenges to wastewater treatment. Pharmaceuticals enter aquatic systems mainly with wastewater via wastewater treatment plants. These emerging contaminants can be removed by introducing biological cleaning systems with plants that grow near secondary wastewater units. This study analyzed the ability of Lemna minor to bioaccumulate four antidepressants: sertraline (SER), fluoxetine (FLU), paroxetine (PAR), and mianserin (MNS). A significant decrease in drug concentrations was observed in the samples with L. minor in comparison with those without plants. Among the tested drugs, L. minor showed the greatest bioaccumulation potential for SER, and the lowest for FLU. The bioconcentration factor for MNS never exceeded 100 L kg–1 even after 7 days, while for SER it was 1,902 L kg–1. These results indicate that L. minor can influence the water treatment process in the natural ecosystem and serve as an effective tool in wastewater treatment for the removal of the analyzed antidepressants.