Pavleno's win sends Ukraine, which only ruled out a boycott of the Games on Friday amid political tension with host nation Russia, to second place in the medal table behind Russia, leapfrogging Germany.
Pavlenko finished in 38 minutes 54.3 seconds to seal her sixth career Paralympic medal and first gold, as well as her first win at a major championships since 2005.
The silver medal went to Ukraine-born Oksana Masters of the U.S, who was 21.7 seconds off Pavlenko's time.
Masters, who was born with multiple impairments linked to the Chernobyl nuclear accident, only took up skiing a year ago after winning bronze in rowing at the London 2012 Summer Paralympics.
Russia took the bronze, with Svetlana Konovalova trailing Pavlenko by 55.5 seconds.
Competing in her first Paralympic skiing event, three-time wheelchair racing gold medalist Tatyana McFadden, a Russian-born athlete competing for the U.S., finished fifth, 1 minute 43.9 seconds off the winning time.
The race used so-called "calculated time," in which each athlete's time is modified by a percentage reflecting the extent of their disability.
Earlier in the day, Russia swept the podium in the men's 15km sitting event, with Roman Petushkov leading home the winning trio, ahead of compatriots Irek Zaripov and Alexander Davidovich.
Over nine days of competition in Sochi, a total of 72 gold medals will be awarded in five sports.