This dataset provides pollen counts for the Holocene lacustrine sedimentary sequence retrieved from Lost Lake, Canada (49.4038, -122.9756, 235 m above sea level). The LLCore2 composite sediment core was collected from Lost Lake, in the Lower Seymour Conservation Reserve, North Vancouver, British Columbia, Canada in fall 2020. The composite core is composed of a 0.41 meter surface core, collected using a Glew gravity corer, and a 2.41 meter sediment core collected using a Livingstone piston corer. The chronology was established using 210Pb, 137Cs, and accelerator mass spectrometry 14C radiometric dating. 1-cm³ volumetric pollen samples were selected at 10-cm intervals along the core, and isolated according to Faegri and Iversen (1989) and Moore et al. (1991). Pollen and spores were counted using a Leica M205C stereomicroscope, and measured against depth (m) and age (ka BP). These data were collected to provide information about local and regional changes in ecosystem composition and fire activity throughout the Holocene in the Lower Mainland of British Columbia.