The two powers have pledged to join forces amid renewed tensions with western nations in recent months, including further financial support from sanctions and concerns about state sovereignty.
Beijing will boost cooperation with Russia as western countries slap further sanctions on Moscow, it was reported on Monday.
"We strongly oppose the use of unilateral sanctions", Chinese Foreign Ministry spokesperson Wang Wenbin said at a press briefing on Monday. "China and Russia maintain relations of comprehensive partnership with each other. China and Russia will support each other in matters of protecting state sovereignty".
The statement comes just days after Wang said at a press conference last Thursday that China would remain committed to international arms control efforts and nuclear disarmament to maintain global stability.
"China stands ready to work with all parties to continue to strengthen communication within the frameworks of the Conference on Disarmament and the mechanism of five nuclear-weapon states, discuss a wide range of issues concerning global strategic stability, and contribute to maintaining international peace and security", he said, responding to press questions on Russian President Vladimir Putin's call for international cooperation on arms control.
The news comes as Washington imposed sanctions on Russia and China this month. The Biden administration also blocked US banks from purchasing Russian government bonds, citing alleged meddling and hacking in the 2020 US elections.
Officials in Moscow have slammed the accusations as baseless and absurd, and expelled 10 US diplomats along with further countermeasures, adding it would respond to all sanctions from the US.
The White House and the European Union also hit China with sanctions over alleged human rights abuses in Xinjiang, which numerous western countries have declared "genocide" in recent months, citing a UN report backed by Human Rights Watch.
Washington also sanctioned China after Beijing passed its Hong Kong national security law aimed at tackling violent secessionist protests gripping the special administrative region.