He secured 47 out of the 59 votes in the House which included 36 votes of the Naga People's Front, 4 of the Bharatiya Janata Party and 7 from the Independents, Speaker Imtiwapang said.
Former chief minister Shurhozelie Liezietsu bagged 11 votes -- 10 of the NPF and one Independent, the speaker said.
He was not present in the assembly as he is not a member.
Zeliang was sworn-in on Wednesday replacing Shurhozelie Liezietsu, who was sacked by Governor P B Acharya.
He was appointed chief minister shortly after Liezietsu and his supporters failed to turn up in the Assembly to face the floor test.