The understanding of the surrounding river impacts on the sediment supply to the Bohai Sea, northern China, is insufficient. In this study, magnetic measurements on surface sediment from the Bohai Sea and surrounding rivers were performed to interpret the distribution and origin of sediment in the Bohai Sea. Different magnetic properties in the analyzed material correspond to seven provenance areas. The magnetic mineral content decreases gradually toward the central Bohai Sea from its marginal areas. Sediment in the central and northern parts contains higher concentrations of finer magnetic minerals than the southern Bohai Sea. The western Bohai Sea (western Bohai and Liaodong bays) has high contents of magnetic minerals because its provenance areas contain abundant old metamorphic rocks with magnetite. The Yellow River, with the most elevated sediment flux, contributes with fine, high-corercivity magnetic minerals (e.g., hematite) to the southern Bohai Sea (mainly in the northwestern Laizhou Bay). Some local rivers (e.g., Fuzhou River) are also important contributors to the coastal waters, due to the magnetic similarities. Sediment from the north Yellow Sea is magnetically similar to the Yellow River detritus. The results highlight the use of the rapid magnetic method in provenance tracing.