Rio had won even before voting in Nagaland Assembly elections as he was elected unopposed after his rival from the Naga People's Front (NPF) withdrew his nomination.
This is the first time so many women were contesting the election in the male-dominated political system in the state. In 2013, there were only two female candidates.
The stunning saffron surge in the Northeast on Saturday decimated the Left in Tripura - one of its last two citadels - with the BJP ousting the CPI-M from power after 25 long years.