In this work, sixteen new pyrrolidinium herbicidal ionic liquids (HILs) with phenoxycarboxylate anions were synthesized and characterized. The effect of the alkyl or alkoxymethyl chain length and type of anion on the physicochemical properties, such as density, viscosity and refractive index of HILs, as well as on the thermal stability and surface activity, were determined. The oxygen presence in the structures of the prepared HILs significantly affects their thermal and surface properties. Furthermore, the herbicidal efficacy was tested in greenhouse experiments by using common lambsquarters (Chenopodium album L.) as a test plant. The novel pyrrolidinium ionic liquids were more effective than the commercial herbicides.