Metagenomic analysis of mosquitoes allows the genetic characterization of mosquito-associated viruses in different regions of the world. This study applied the metagenomic approach to search for novel viral sequences in seven species of mosquitoes collected from the Novosibirsk region of Western Siberia. Using NGS sequencing, we identified 15 coding-complete viral polyproteins (genomes) and 15 viral-like partial sequences in mosquitoes. The complete sequences for novel viruses or partial sequences of capsid proteins, hypothetical viral proteins, and RdRp were used to identify their taxonomy. The novel viral sequences were classified within the orders Tymovirales and Picornavirales, the families Partitiviridae, Totiviridae, Tombusviridae, Iflaviridae, Nodaviridae, Permutotetraviridae, Solemoviridae, with several attributed to four unclassified RNA-viruses. The main part of the novel putative viruses and viral sequences was associated with Coquillettidia richardii mosquito. This study is intended to increase our understanding of viral diversity in mosquitoes found in the natural habitats of Siberia, characterized by very long, snowy, and cold winters.