Moses has not played for Chelsea since September 2018 and has spent the last two seasons on loan at Fernerbahce and Inter Milan.
The 29-year-old joined Chelsea from Wigan Athletic in the summer of 2012 but has not been a regular for most part of his stay at Stamford Bridge.
His most consistent run in the Chelsea team came under Antonio Conte between 2016 and 2018, as he was utilized in a right wing-back role and helped the Blues win the Premier League and FA Cup under the Italian manager.
In addition to his temporary spells in Turkey and Italy, Moses has also spent time on loan at Liverpool, West Ham United and Stoke City.
"Victor Moses has joined Spartak Moscow on loan for the remainder of the 2020/21 campaign," Chelsea revealed in a statement published on the club's official website.
"The Russian side are 10 games into their league season and sit second in the table, level on points with city rivals CSKA Moscow.
"Spartak also confirmed the move, writing on the club's Twitter page: "Victor Moses is a Spartak player!
"Spartak Moscow and Chelsea have agreed the transfer of Nigerian star Victor Moses to our club. The loan agreement with the 29-year-old midfielder is until the end of the season with the option to buy! Welcome, Victor!"
Moses helped Nigeria win the Africa Cup of Nations in 2013.
