Four new species of Marphysa are described from Terengganu state on the east coast of Peninsular Malaysia, using morphological and molecular (cytochrome oxidase subunit I (COI) gene) data. These species belong to different groups of Marphysa: Marphysa kertehensissp. nov. belongs to Group A (Mossambica), Marphysa merchangensissp. nov. and Marphysa setiuensesp. nov. belong to Group B (Sanguinea) and Marphysa ibaiensissp. nov. belongs to Group E (Gravelyi). Marphysa kertehensissp. nov. is characterised by having only limbate chaetae, absence of subacicular hooks, three types of pectinate chaetae including wide, thick isodont with short and slender inner teeth, and pectinate branchiae with up to nine branchial filaments. Marphysa merchangensissp. nov. is characterised by the presence of eyes, unidentate subacicular hooks, four types of pectinate chaetae including wide, thick anodont pectinate chaetae with five long and thick inner teeth, and pectinate branchiae with up to six branchial filaments. Marphysa setiuensesp. nov. has mostly unidentate subacicular hooks (bidentate on several posterior chaetigers), four types of pectinate chaetae including wide, thick anodont pectinate chaetae with seven thick and long inner teeth, and pectinate branchiae with up to five branchial filaments. Marphysa ibaiensissp. nov. has bidentate subacicular hooks throughout, five types of pectinate chaetae, including a heterodont with 12 short and slender inner teeth, and pectinate branchiae with up to eight branchial filaments. The designation of these new species based on morphology is fully supported by molecular data. Habitat descriptions of each species are also included.