Time-series datasets showing the gradual conformational change in the status and characteristics of microplastics (MP) in marine waters are needed to protect vulnerable marine ecosystems. In this study, the abundance, spatiotemporal distribution, polymer composition, size, and shapes of the MP in the seawater sampled from 0.5 (station-1), 2.5 (station-2), and 5 (station-3) miles off the coast of the southeastern Black Sea between 2009 and 2020 were investigated. The abundance of the MP ranged from 0.181 to 0.944 m−3. The amounts of MP in the stations, from the greatest to the smallest, were 0.65 MP m−3 (2), 0.45 MP m−3 (1), 0.29 MP m−3 (3). Thirteen types of polymers were detected by FTIR, the most abundant types of which were polyethylene (44.9%) and polyethylene terephthalate (25.3%). Sizes of MP ranged from 118 to 4998 μm, 50% being smaller than 2000 μm. The most dominant shape of the MPs was fragments (56.3%). Abundance did not show significant spatiotemporal changes. Periodical data presented herein may represent a remarkable projection and create a baseline for the ecosystem's future functioning and pollution research in the Black Sea.