The Arctic ecozone is undergoing rapid and major change in response to climate change. Establishing a baseline of current Arctic vascular plant diversity and distribution is necessary to be able to track changes in species composition over time due to climate change. Here, we report the results of a floristic study of vascular plant diversity of Katannilik Territorial Park and Kimmirut and vicinity on southern Baffin Island in the Canadian Arctic Archipelago, Nunavut, Canada. The study area is located within Circumpolar Arctic Bioclimate Subzone D. The study is based on a dataset comprising 1571 collections from the study area gathered over the last century, including 838 collections we made during fieldwork in 2012. We present the results in an annotated checklist. The vascular plant flora of the study area comprises 34 families, 98 genera, 210 species, three nothospecies, and seven infraspecific taxa. We recorded 190 species, five infraspecific taxa, and two nothospecies from Katannilik Territorial Park and 162 species, five  infraspecific taxa, and two nothospecies from Kimmirut. We newly record 46 species and one infraspecific taxon in 21 families from the study area, including 11 taxa (prefaced by an asterisk) we reported in an earlier publication: Erigeron eriocephalus, Taraxacum holmenianum (Asteraceae), Draba arctica, D. fladnizensis, D. corymbosa, D. lactea (Brassicaceae), *Arenaria longipedunculata, Honckenya peploides subsp. diffusa, Sabulina rossii, Silene uralensis (Rupr.) Bocquet subsp. uralensis, Viscaria alpina (Caryophyllaceae), *Carex brunnescens subsp. brunnescens, C. microglochin, C. krausei, C. subspathacea, Eriophorum scheuchzeri subsp. arcticum (Cyperaceae), *Andromeda polifolia, *Orthilia secunda subsp. obtusata (Ericaceae), Oxytropis podocarpa (Fabaceae), *Triglochin palustris (Juncaginaceae), *Utricularia ochroleuca (Lentibulariaceae), Luzula groenlandica (new to the Canadian Arctic Archipelago), Huperzia continentalis (Lycopodiaceae), Montia fontana (Montiaceae), Hippuris lanceolata, H. vulgaris, Plantago maritima (Plantaginaceae), Calamagrostis purpurascens, C. neglecta subsp. groenlandica, Festuca prolifera var. lasiolepis (new to the Canadian Arctic Archipelago), F. rubra subsp. rubra, F. rubra subsp. arctica, *Hordeum jubatum subsp. jubatum, *Leymus mollis subsp. mollis (Poaceae), *Cryptogramma stelleri (Pteridaceae), *Corallorhiza trifida, *Platanthera obtusata subsp. obtusata (Orchidaceae), *Coptidium ×spitsbergense (Ranunculaceae), Potentilla crantzii, P. hyparctica subsp. hyparctica, Rubus chamaemorus, Sibbaldia procumbens (Rosaceae), Salix fuscescens (Salicaceae), Micranthes foliolosa, M. nivalis (Saxifragaceae), and Woodsia alpina (Woodsiaceae). All species in the study area are native except two grasses we recorded in Kimmirut: F. rubra subsp. rubra, which was likely seeded, and Hordeum jubatum subsp. jubatum, of unknown origin. We summarize the known distribution on Baffin Island for each taxon recorded from the study area, including several previously unpublished records on southern Baffin Island.