Mr Tshibala will be leader until presidential elections later this year.
He was expelled from Congo's largest opposition party, the UDPS, last month after contesting the designation of successors to veteran leader Etienne Tshisekedi who died in February.
Mr Tshibala's appointment is likely to further divide Mr Kabila's opponents.
Talks to negotiate his exit from power broke down last week.
Mr Kabila was supposed to step down after his second and final five-year term came to an end last year but the vote to replace him was not held.
