The 52-year-old leader is also an MLA from the state replaces Ravindra Kumar Ray, who is a Lok Sabha MP.
Das is the first non-tribal chief minister of the state and the party has reached out to the Scheduled Tribes by appointing Marandi as its state chief.
"Our National President has appointed Tala Marandi as the state unit chief," state party spokesman Pradip Sinha said in Ranchi.