A senior legislator and former minister, Karthikeyan defeated CPI(M)`s AK Balan securing 73 votes against the latter`s 68.
The votes received by the rival candidates tallied the strength of their respective coalitions, which stood at 73-68 after the nominated Anglo-Indian member Ludy Luiz joined the treasury benches. Luis took oath as MLA along with the 140 elected members yesterday.
The result was announced by pro tem Speaker N Sakthan who presided over the proceedings.
61-year-old Karthikeyan, a six-time legislator, was elected in the April 13 Assembly polls from Aruvikkara segment in Thiruvananthapuram district.
His experience, ability and acceptability within and outside the ruling coalition worked for his selection as Speaker, whose job is crucial considering the slender majority the government commands in the House.
Karthikeyan has served as minister in some of the previous UDF governments handling important portfolios like Power, Civil Supplies and Cultural Affairs.
He entered politics through the Congress` campus wing, Kerala Students Union, and later headed the Youth Congress in the state.