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Fjords on the West Antarctic Peninsula (WAP) serve as sediment traps, preserving histories of glacial sediment supply. Regional warming trends are expected to change sediment supplies, altering water quality, depositional history, and ecosystem drivers. Our ability to assess magnitudes of these changes is limited by sparse data on modern sediment accumulation. Twelve new cores and four existing cores from Andvord Bay were used to characterize variability in sediment accumulation rates. These range from 1.5 to 7.9 mm/year (0.12 to 0.56 g·cm−2·year−1). Spatial differences and a weak down‐fjord gradient in rates suggest diverse sediment sources, including from outside the fjord. This data set provides a comprehensive assessment of sedimentation during the past century, indicating little change in rates due to recent WAP warming, and sets a benchmark for assessing climate‐related changes in sediment delivery and ecosystem drivers (e.g., burial disturbance) in the fjord over coming decades. Plain Language Summary: Tidewater glaciers commonly carve deep fjords, which fill with sediment as the glaciers retreat. Rates of fjord sediment accumulation increase from polar to temperate latitudes because glaciers become more erosive due to increases in air (and water) temperatures and more abundant subglacial meltwater. Presently, subpolar glaciers on the West Antarctic Peninsula (WAP) are weakly erosive, and adjacent fjords host high levels of biological diversity and abundance. Sediment delivery and seabed disturbance are expected to increase with regional climate trends; unfortunately, we have sparse information on present sediment accumulation rates. In this study, we collected a large set of cores and constructed a detailed picture of sediment properties in Andvord Bay on the WAP. Sediment accumulates at slow rates of millimeters per year, conditions which foster great biologic productivity in the WAP coastal zone. These data provide a critical foundation for assessing the sedimentation disturbance regime in Andvord Bay. Key Points: Sediment accumulation rates in Andvord Bay (Antarctica) are only millimeters per year and are spatially variable, reflecting slow delivery from diverse sourcesLimited evidence exists of sporadic gravity flows adjacent to the two primary tidewater glaciersSeabed radioisotope profiles do not indicate any substantial changes in sediment accumulation rates over the past century [ABSTRACT FROM AUTHOR]