The Foxes moved swiftly to make the Nigeria international their fourth signing of the summer after he hit 13 goals in 30 league games for CSKA last term.
The 23-year-old joins Nampalys Mendy, Ron-Robert Zieler and Luis Hernandez as boss Claudio Ranieri looks to build on his side's stunning title triumph last season
Musa told Foxes Player HD: "I feel very happy joining Leicester City, for me it's one of the best clubs and I feel very happy
I joined because it's one of the best clubs in the Premier League and they are like a family
That's why I joined Leicester City and I'm very excited
"I look forward to seeing the fans in the new season and I will do my best to make them happy."
Musa moved from Nigeria to Dutch side VVV Venlo in 2010 before catching the eye of CSKA two years later and becoming a permanent fixture in the Russian Premier League.
He has also scored 11 goals in 58 games for his country, including a brace against Argentina in the 2014 World Cup.
Source : PA
Source: PA