Ravi, a three-time legislator, got 74 votes against E Chandrasekheran, CPI candidate of LDF who polled 65 votes.
The original strength of the House is 141 including a nominated Anglo-Indian member. However, the present strength is 140 after a rebel Kerala Congress (M) MLA P C George was disqualifed for his anti-party activities recently.
CPI-M member Thomas Issac did not take part in the voting as he was absent.
Ravi represents Nedumangad segment in Thiruvananthapuram district.
Election to the Deputy Speaker's post was necessiated after N Sakthan was elevated as Speaker following the death of the then Speaker G Karthikeyan in February last.