Russia's parliament approved a law on Wednesday in double-quick time removing the upper age limit for contractual service in the military, amid heavy casualties in Ukraine.
Lawmakers in the State Duma lower house approved the bill in three readings in a single session, with the upper house, the Federation Council, giving its assent shortly after.
The bill now needs only the signature of President Vladimir Putin to become law.
State Duma speaker Vyacheslav Volodin said: "Today, especially, we need to strengthen the armed forces and help the Ministry of Defence. Our Supreme Commander is doing everything to ensure that our armed forces win, and we need to help."
Currently, only Russians aged 18-40 and foreigners aged 18-30 can enlist as professional soldiers in the Russian military.
Russian forces have suffered significant losses fighting in Ukraine.
The defence ministry said on March 25 that 1,351 Russian service personnel had been killed and 3,825 wounded since Moscow sent its armed forces into Ukraine on February 24. It has not updated its casualty figures since.
Both Ukrainian and Western intelligence officials have said Russia's losses in Ukraine were significantly higher at the time, and have risen sharply since March.