Processed sampling data for microplastics in sediment samples in beach sediments and seabed sediments in sampling stations in Burgas Bay, SE Black Sea. Urban coastal areas (S1- Sozopol Bay) had the highest average MP concentrations (464.44±272.50 MP.kg-1 dry sediment in beach samples, 825.93±396.30 MP.kg-1 dry sediment in seabed samples), while coastal sediments in an area with no local anthropogenic activities (S2, Paraskeva Bay) had significantly lower average MP concentrations (184.44±147.57 MP.kg-1 in beach samples, and 550.62±245.71 MP.kg-1 in seabed samples).