Opposition lawmakers boycotted the vote on December 23, while the parliamentary majority representing the ruling Democratic Party voted for the agreement’s ratification.
Hundreds picketed the parliament in Yerevan, protesting the ratification of the agreement signed earlier this month.
The deal gives the Russian energy giant Gazprom, which already owns 80 percent of the ArmRosgazprom Armenian-Russian joint venture, the remaining 20 percent.
Gazprom will also control all Armenian gas imports until 2043.
Armenian President Serge Sargisian, who announced in September Yerevan’s decision to join a Russian-led customs union, traveled to Moscow on December 23 to take part in the session of the Supreme Eurasian Economic Council, the customs union’s governing body.