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In recent years, plant growth-promoting rhizobacteria (PGPR) have received increased attention due to their prospective use as biofertilizers for the enhancement of crop growth and yields. However, there is a growing need to identify new PGPR isolates with additional beneficial properties. In this paper, we describe the identification of a new strain of a non-sporulating Gram-positive bacterium isolated from the rhizosphere of potato plants, classified as Brevibacterium sediminisMG-1 based on whole-genome sequencing. The bacteria are aerobic; they grow in a pH range of 6.0–10.0 (optimum 6.0), and a temperature range of 20–37 °C (optimum 30 °C). At 96 h of cultivation, strain MG-1 synthesizes 28.65 µg/ml of indole-3-acetic acid (IAA) when 500 µg/ml of l-tryptophan is added. It is a producer of catechol-type siderophores and ACC deaminase (213 ± 12.34 ng/ml) and shows halotolerance. Treatment of pea, rye, and wheat seeds with a suspension of MG-1 strain cells resulted in the stimulation of stem and root biomass accumulation by 12–26% and 6–25% (P< 0.05), respectively. Treatment of seeds with bacteria in the presence of high salt concentration reduced the negative effects of salt stress on plant growth by 18–50%. The hypothetical gene lin,encoding the bacteriocin Linocin-M18, RIPP-like proteins, and polyketide synthase type III (T3PKS) loci, gene clusters responsible for iron acquisition and metabolism of siderophores, as well as gene clusters responsible for auxin biosynthesis, were identified in the B. sediminisMG-1 genome. Thus, the rhizosphere-associated strain B. sediminisMG-1 has growth-stimulating properties and can be useful for the treatment of plants grown on soils with high salinity.