Pun was today elected as the country's vice president after winning 325 out of 547 votes.
His rival Amiya Kumar Yadav of Nepali Congress, received 212 votes, announced Speaker Onsari Gharti at the Parliament. Ten votes declared invalid.
Pun succeeded Parmananda Jha, who belonged to one of the major Madhesi parties. Pun was born in Rolpa district.
He was the chief commander of the Peoples Liberation Army of the Maoist party during the decade long insurgency.
The lawmakers belonging to the Joint Democratic Madhesi Front (UDMF) did not take part in both the presidential and vice-presidential elections after showing participation in the prime minister's election.
He soon became the district president of the youth wing of the party which played a vital role in launching the People's War in 1996. He was later appointed as one of the four deputy commander of the People's Liberation Army (PLA) and commanded several battles against the then Royal Nepal Army.
Vidya Devi Bhandari from the ruling CPN-UML was elected as Nepal's first woman President on October 28 after she defeated her rival from Nepali Congress by more than 100 votes.