He belongs to the Wiper Democratic Movement and was elected to represen Mwingi South Constituency in the National Assembly of Kenya since the Kenyan parliamentary election of 1997.
He is currently a senator representing Kitui County.
Musila was a DO, DC and deputy PC between 1966 and 1979.
In 1979, he was Moi's choice as PC for the troubled Central Province, a post which he retained until 1985, after which he became Director of Tourism.
He retired from the civil service in 1988.
He was elected as a KANU MP in 1997 and has remained in the house ever since, moving to the LDP wing of NARC in 2002, and was Deputy-Speaker in the 2003 Parliament.
He was a KANU official in the 1990s and later became Deputy Chairman and then Chairman of the Liberal Democratic party (LDP).