The victory was marked with the support of 32 of the total 60 MLAs in the Manipur Assembly.
Governor Najma Heptulla administered the oath of office and secrecy to Singh at a function in Raj Bhavan here.
“It is a great challenge. The people have given the mandate for a change and I assure that our team under the leadership of Prime Minsister Narendra Modi will surely provide good governance,” Singh said.
The Congress is leading on 11 seats, the BJP on nine, Nationalist Congress Party (NCP) on one and others on seven seats respectively.
PRAJA (Peoples’ Resurgence and Justice Alliance) chief Irom Sharmila has lost from Thoubal constituency, where she was contesting against incumbent Chief Minister Okram Ibobi Singh.
The Election Commission has issued guidelines on security arrangements for counting of votes, and has also set up facilities for disseminating trends and results of elections of five assemblies.
The polling started at 7 this morning and will conclude at 3 in the afternoon.
The human rights activist-turned-politician had earlier during the first phase of polling expressed confidence about winning the Manipur polls.
Polling for 22 assembly seats spread across ten districts is being held under tight security from seven in the morning till three in the afternoon.