Abstract Mud depocenters in shelf seas serve as a key element in the source‐to‐sink system of sediment transport on the Earth surface. Despite their undoubtful importance, physical mechanisms for formation, sediment budgeting, and cycling of localized depocenters in high‐energy environments remain largely unknown. This study aims to fill the knowledge gap by focusing on sediment dynamics related to a localized mud depocenter in the southern North Sea. By combining field observation with 3‐dimensional numerical simulations, we analyzed hydrodynamics and sediment dynamics over a 3‐year period. Our results indicate a persistent transport of fine‐grained sediments toward the depocenter and subsequent trapping resulting in accumulation, with distinct seasonal and spatial variations in the net depositional rate. The interaction of wind‐driven coastal circulation with two distinct frontal systems—a salinity front and a tidal mixing front—emerges as a key mechanism of sediment dynamics. While the salinity front remains persistently over the depocenter, promoting sediment deposition year‐round, the tidal mixing front appears primarily in summer, limiting sediment deposition. Sediment flows from offshore and along the coast provide major supply to the depocenter, while contemporary riverine sediment outflows contribute only marginally. Southwesterly winds enhance erosion and northerly winds promote deposition in the depocenter. Additionally, short‐term extreme events significantly contribute to annual net sedimentation. Our work highlights the critical importance of frontal systems and extreme events for mud depocenter development in high‐energy shelf seas. Plain Language Summary Coastal environments constantly change as water moves sediment, forming areas where mud accumulates, known as mud depocenters. However, the processes controlling development of these deposits are not fully understood. This study examines a mud depocenter in the southern North Sea to understand how ocean currents, river flow, tides, and wind influence sediment movement. We found that two key oceanic density fronts—a riverine salinity front and a tidal mixing front—play a crucial role in trapping sediment. The salinity front is present year‐round, while the tidal front appears mainly in summer. The contrasting effects of these two fronts lead to higher sediment accumulation in winter. Wind direction also affects deposition, with southwesterly winds causing erosion and northerly winds promoting deposition. Extreme events like storms and river floods significantly increase sedimentation over short periods. Our results highlight the critical importance of frontal systems and extreme events that shape coastal sedimentation in high‐energy shelf seas. Understanding these processes is especially important for predicting coastal changes, as human activities may also influence sediment dynamics. Key Points Salinity and temperature frontal systems jointly control sediment trapping and deposition in energetic shelf seas Despite seasonal variations in the frontal systems, persistent sedimentation occurs in the mud depocenter Sedimentation on the mud depocenter is promoted by storms and floods