The current knowledge on the treatment of resorcinol-and nitrogen-containing wastewater in different treatment wetlands is limited. This study investigated three laboratory-scale treatment wetlands, namely, floating wetland, planted wetland and unplanted wetland, treating artificial wastewater containing resorcinol and ammonium. Under the inflow resorcinol concentration of 10 mg/L, these wetlands exhibited a removal efficiency of approximately 94% on average, with a specific area removal rate of 260 mg/(m²·d), regardless of wetland type and the presence of plants. These results suggest that treatment of resorcinol-containing wastewater by wetlands is a low-cost and ecological alternative. Compared with the dynamics of ammonium in the unplanted wetland, the high ammonium removal rate (>95%) observed for the planted and floating wetlands strongly indicated that the plants stimulated ammonium oxidation processes mainly by releasing oxygen from the roots. Acidification at pH 3, which can be attributed to an active nitrification process and the secretion of hydrogen ions by the plant roots, was observed in the floating wetland. The low pH buffer capacity could be caused by the low content of dissolved inorganic carbonates, and the use of substrate may act as a barrier to prevent rapid diffusion of carbon dioxide from the pore water to the atmosphere. The significant nitrate accumulation rate of 20 mg/L noted in the floating wetland indicated a limited denitrification process due to the high redox condition (600 mV). A better oxygenated condition for the floating wetland is beneficial to oxidation removal of organic compounds and ammonium, but it may not be good for such reduction processes as denitrification.