<p>The halophytic vegetation on the coasts of the White and Barents Seas (Arctic Ocean) is diverse, as it develops under heterogeneous conditions influenced by both ocean and land. Currently, little is known about the distribution of phytocenoses in saline biotopes on these coasts. The obtained picture of the halophyte vegetation structure will help to elucidate the distribution patterns of coastal phytocenoses across the biotopes of the White and Barents Seas. From the perspective of the ecological-phytocenotic approach, 40 associations were identified on the coasts based on the similarity of plant community structure and composition. Vegetation ordination performed using non-metric scaling, shows the correspondence of plant communities to specific biotope types: salt marshes, brackish marshes, beaches and dunes, saline lagoon lakes, and tidal flats at the heads of estuaries. In this paper, using ordination analysis, we propose for the first time a classification of brackish marshes into coastal-water and near-water brackish marshes, which enriches the general classification of marsh biocenoses. Salt marsh biotopes exhibit the greatest phytocenotic diversity, with 21 associations of seaside vegetation identified. The species composition and halophyte vegetation structure are similar in the biotopes of the Arctic marshes of the Mezen Bay and the Cheshskaya Bay estuaries, but these communities differ significantly from the boreal-type marshes on the southeast coast of the Dvina Bay and Onega Bay. The living conditions for plants of different ecological groups in coastal communities are not uniform. Obligate halophytes develop under stable water salinity and pH conditions. Facultative halophytes are able to live in environments with wide pH and salinity ranges.</p>