After trailing by 14, Lithuania was within six in the fourth when Sergei Monya hit a 3-pointer for Russia, and Kirilenko, who signed a two-year contract with the Minnesota Timberwolves this summer, converted a three-point play with 1:42 remaining.
Lithuania, which lost by only five points to the U.S. in pool play, was still within five in the final minute, but missed two free throws and Russia ended the game on a 6-0 run.
Rimantas Kaukenas scored 19 and Darius Songaila 15 for Lithuania, which has not won a medal since getting bronze in 2000.
Russia won its group in the preliminary round, beating medal favorites Brazil and Spain in the process. Those tight wins gained the Russians a few believers, but most international hoop experts didn't think they belonged in the same company with the Americans, Argentina, Spain, France or Brazil.
"We've been outside that circle," David Blatt, Russia's American-born coach, said earlier in the tournament.
Russia's now on the inside.
With size and depth, the Russians, who have never won an Olympic medal in basketball as an independent nation, will be a handful for whomever plays them next.
Russia, involved in three games decided by three points or less in the preliminary round, let a 14-point lead in the third quarter dwindle to two early in the fourth when Lithuania 7-foot-center Jonas Valanciunas, who will play for Toronto next season, scored inside to cut the Russians' lead to 57-55.
But Monya hit a pair of 3-pointers and Russia's frontline made it tough for Lithuania to get off any shots close to the basket. The Russian big men contained Lithuania's Linas Kleiza, who scored just four points on 1 of 7 shooting.
Despite being cheered on by their flag-waving, face-painted, whistling fans the international game's version of Duke's Cameron Crazies Lithuania started poorly. The Lithuanians made just 3 of 16 shots and scored nine points during a dreadful performance in the first quarter.
Russia built nine-point lead and appeared in control. But known for their discipline, the Russians, who beat Lithuania in two exhibition games leading into London, got a little too carefree.
"Stop settling for jump shots," screamed Blatt.
But it was too late, and Lithuania began chipping away with Songaila doing the dirty work down low.
The former Washington Wizards forward scored 10 points in the second quarter as Lithuania pulled within 32-27 at the break.