"We want development and we will work very hard to settle the Naga political issue at the earliest," Rio told reporters after taking oath as the CM at the Kohima Local Ground.
Earlier, while addressing the people that had gathered to witness the swearing-in ceremony, Rio said, "We will extend our fullest cooperation to the Government of India under the dynamic leadership of Prime Minister Narendra Modi in our collective endeavour to bring lasting peace in Nagaland."
Rio, who returned to state politics after a gap of almost four years after resigning from the Lok Sabha in 2014, also said that his government would ensure that the "votes cast in his party's favour do not go in vain".
"We will bring change, we will work for all sections and we will leave no one behind. Thank you for your blessings and your support," he stated.
The People's Democratic Alliance (PDA) has come to power on the back of a campaign that promised change, he said while assuring "good governance, transparency and a culture of meritocracy".
The PDA comprises 18 members from the NDPP, 12 from the BJP, one from the JD(U) and an Independent.
"We recognise that this mandate is not just for a change in the government but to bring positive changes in Nagaland," he said, while affirming that the new government will redraw a new roadmap of progressive development in a manner that is all inclusive and involves all stakeholders.
Iterating one of the promises made by the NDPP in its election manifesto, Rio said his government will remove VIP culture from Nagaland and ensure that the citizens are treated as "real VIPs".
"For us, the people and the masses are our high command. We assure the people of Nagaland that we will tirelessly work towards fulfilling the promises made to the people," he said.
The new CM also promised to maintain "harmonious" relationships with other states in the Northeast in the greater interest of the Naga people.