This study evaluated the effect of polyethylene (PE) microplastics on the removal of Cr(VI) by activated carbon (AC) in aqueous media. At an AC dosage of 1.6 g/L, the AC-only treatment removed 17.0% of the Cr(VI) from the initial Cr(VI) solution (100 mg/L; pH 5) within 12 h. This increased to 21.8% and 17.7% in the AC–PE treatment (AC dosage of 1.6 g/L) with a PE dosage of 0.8 g/L and 4.8 g/L, respectively. At an AC dosage of 4.8 g/L, the AC-only treatment removed 21.3% of the Cr(VI) from the initial Cr(VI) solution after 12 h. However, in the AC–PE treatment (AC dosage of 4.8 g/L) with a PE dosage of 0.8 g/L and 4.8 g/L, 17.6% and 24.7% of the Cr(VI) was removed, respectively. The different influences of the PE microplastics on the removal of Cr(VI) by the AC were attributed to i) the variable adsorption of Cr species to the PE microplastics at the lower AC dosage, and ii) the formation of an AC coating on the surface of the PE at the higher AC dosage. The pH of the aqueous medium slightly affected the removal of Cr(VI), which reduced from 26.7% at pH 2 to a minimum of 19.5% at pH 7 for a AC dosage of 1.6 g/L and PE dosage of 0.8 g/L. The results of this study provide a basis for future mechanistic investigations concerning the interaction of microplastics and carbon-based adsorbents for the remediation of wastewater containing heavy metal(loid)s..