Heterotrophic nitrification–aerobic denitrification (HN-AD) is an efficient nitrogen removal process and the genusParacoccusis one important group of the HN-AD bacteria. During an investigation of the microbial diversity in marine ranching of the Pearl River Estuary (PR China), three bacterial strains, designated SCSIO 75817T, SCSIO 76264Tand SCSIO 80058T, were isolated from sediments. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the three strains belonged to the genusParacoccusand their closest neighbors wereP. isoporaeDSM 22220T(97.6–98.0%),P.aurantiacusCGMCC 1.13898T(97.3–97.6%) andP.xiamenensisMCCC 1A16381T(97.1–97.4%), respectively. The analysis results of 16S rRNA gene similarity, ANI, AAI and dDDH showed that the pairwise similarities between these three strains and their closest neighbors were 97.4–98.5%, 76.9–81.0%, 75.5–79.6% and 20.3–23.3%, respectively. Polyphasic taxonomic data of the phylogenetic, phenotypic and chemotaxonomic analyses indicate that these strains represent three novel species in the genusParacoccus, for which the namesParacoccus aerodenitrificanssp. nov.,Paracoccus sediminicolasp. nov. andParacoccus albussp. nov. are proposed, respectively. The study also demonstrated the heterotrophic nitrification–aerobic denitrification (HN-AD) ability of the novel speciesP. aerodenitrificansSCSIO 75817T. When it was aerobically cultivated at 28 °C using NH4+-N, NO3−-N and NO2−-N as the sole nitrogen sources, the nitrogen removal efficiencies were 73.4, 55.27 and 49.2%, respectively, and the maximum removal rates were 3.05, 1.82 and 1.63 mg/L/h, respectively. The results suggest that it has promising potential for wastewater treatment.