A giant piston core MRS-CS27 sedimentary sequence in the Sea of Marmara (SoM) was investigated by palynological analysis to evaluate the paleoenvironmental and climate changes, corresponding to the Marine Isotope Stages MIS-5 (c-a), MIS-4, MIS-3, and the earliest part of the MIS-2. During MIS-5c, the palynological analysis indicates a warm and humid climate in the SoM. The pollen assemblage is characterized by the presence of broad-leaved deciduous woody taxa, with a predominance of deciduous Quercus. Following MIS-5c, a relatively colder and drier climate is inferred during MIS-5b, as indicated by the herbaceous assemblages found in the sedimentary sequence. The presence of herbaceous plants in the pollen record suggests less favorable conditions for woody vegetation and a shift towards a cooler and drier climate compared to the previous phase. Within the MIS-5a interval, the palynological analysis reveals the presence of abundant mesophyllous woody taxa. This indicates a return to a warm and humid climate during this period, supporting the growth of diverse forest vegetation. Distinct changes in vegetation are observed during MIS-4, with the presence of abundant Cedrus pollen. This suggests the survival of montane trees in the region under a cooler climate compared to the previous stages. Relict plants such as Cathaya, Tsuga, and Carya are identified during MIS-3 and MIS-4. Their presence can be attributed to the reworking of older sediments during these periods, indicating that these plants were not contemporary with the sediment but were preserved from earlier time periods.