K.P. Sharma Oli will head the first government elected under a new national constitution that cements Nepal's transformation from a Hindu monarchy to a federal republic.
PM Deuba's address to the nation was expected on Wednesday evening, but was postponed for today since the EC submitted the results quite late, at around 8:00 pm.
The left alliance leaders had visited President Bhandari to present majority to appoint Oli as the Prime Minister.
As per reports, a standing committee meeting of the UML on Wednesday made a decision to field the party's Chairman K P Sharma Oli as the new prime minister on behalf of the left alliance comprising the UML and the Maoist Center.
Olis party CPN-UML secured 121 seats in the 275-member Parliament and became the largest party in the Parliament.
Deuba served as the prime minister from 1995 to 1997, from 2001 to 2002, and from 2004 to 2005.
It must be noted that the Deuba-led Nepali Congress (NC) stood third in the historic parliamentary and provincial assembly polls.
A surprise alliance of Maoist former fighters and the CPN (UML) registered a surprise victory in December.
While the election for Nepal's new president would be held on 5 March, the vice president would be elected on 16 March, they said.
A Standing Committee (SC) of the party held in Lalitpur named Oli as the prime ministerial candidate as he is also the UML's Parliamentary Party leader, Surendra Pandey was quoted as saying by The Kathmandu Post.
The polls are said to be a step forward in cementing democracy and providing political stability to Nepal, which has seen 10 prime ministers in as many years.
This is unedited, unformatted feed from the Press Trust of India wire.