This dataset contains benthic foraminiferal assemblage data, diversity indices, and geochemical proxy records from sediment core KB22-237-06MC-H (60.824°N, 5.344°E; 300 m water depth), collected during cruise KB22-237 aboard R/V Kristine Bonnevie in February 2022 from Masfjorden, western Norway. The dataset includes benthic foraminiferal counts, relative abundances (%), absolute abundances (individuals g⁻¹ dry sediment), percentages of productivity-related taxa, Shannon–Wiener (H) and Dominance (D) diversity indices, loss-on-ignition (LOI550), and carbonate content (CaCO₃). The sediment record spans ca. the last 500 years, covering the period since ca. 1500 AD. The data were collected to reconstruct long-term changes in primary productivity, organic matter flux, and benthic ecosystem functioning in Masfjorden, and to investigate the response of a fjord strongly influenced by Atlantic Water to regional climatic variability over the past five centuries. Sediment cores were retrieved using a multicorer system and subsampled at 0.5 cm intervals. Benthic foraminifera were identified and counted in the >63 μm sediment fraction following standard micropaleontological procedures, while organic matter and carbonate contents were determined using loss-on-ignition analyses. The dataset provides a long-term record of benthic environmental variability and forms the basis for reconstructing productivity changes and ecosystem responses in western Norwegian fjords.