The Baltic Sea-Skagerrak region exhibits strong coupling with North Atlantic climate over recent glacial-interglacial cycles. However, a lack of long, continuous, high-resolution climate records has hindered detailed understanding of this linkage. This study combines ultra-high-resolution sediment core data from Site M0060 (IODP Expedition 347) in the Kattegat seaway to reconstruct seawater environmental changes near the Fennoscandian Ice Sheet (FIS) during the last deglaciation. We present benthic foraminiferal stable isotopes (δ¹⁸O and δ¹³C), trace elements, and assemblage data to assess bottom-water conditions from ~17.6 to 13.3 ka BP. Three stepwise salinity decreases were identified: a rapid freshening at ~17.5 ka, followed by smaller events at ~17.1 and ~16.4 ka. Salinity dropped by ~10 units during the first 2000 years, reflecting a fjord-like setting with strong stratification, poor bottom-water ventilation, and sea-ice formation. After ~15.5 ka, conditions shifted to more saline, warmer, and better-ventilated waters, preceding the Bølling-Allerød warming. The freshening events align with meltwater discharges from the FIS and European ice sheets, with the latter two events (~17.1 and 16.4 ka) closely matching large δ¹⁸O changes in the North Atlantic and Nordic Seas. These findings indicate regional impacts rather than local phenomena. Additionally, the timing and magnitude of the freshening events suggest their role in initiating Heinrich Event 1, specifically HE1.1 (~17.1-15.5 ka BP). This study highlights the FIS’s significant influence on regional and North Atlantic climate interactions during the last deglaciation.