Abstract Bryophytes play a crucial role in the ecosystems of polar regions. These simple plants are among the predominant vegetation types in both Arctic and Antarctic landscapes, where they contribute significantly to biodiversity and ecological stability. Here, we report the chromosome-level genomes of two polar moss species, the Arctic Aulacomnium turgidum and Antarctic Polytrichastrum alpinum. Utilizing a combination of Illumina short reads, Nanopore long reads, and Hi-C data, we assembled genomes of 277.84 Mb for A. turgidum and 498.33 Mb for P. alpinum, respectively. These assemblies were anchored to 11 chromosomes for A. turgidum and 8 chromosomes for P. alpinum. Both species exhibited a sex chromosome with distinct genomic characteristics. Gene annotations revealed 25,999 protein-coding genes in A. turgidum and 28,070 in P. alpinum. The high completeness of the gene space was validated via BUSCO, achieving impressive scores of 98.2% and 98.0%. These high-quality genomes provide critical resources for studying the adaptive evolution and stress tolerance mechanisms of mosses in extreme polar environments.