The 29-year-old is on loan from Premier League side Liverpool, but Hertha will be in no hurry to give the Ukrainian back after he followed up last week's hat-trick against Energie Cottbus with the goal which earned the team three points.
His goal after 50 minutes was at least partly due to good fortune after Leverkusen's Germany goalkeeper Rene Adler went to kick the ball away, but it rebounded off Voronin's chest into the net to claim his 11th goal in 20 games.
Hertha's recent run has boosted attendance at Berlin's Olympic Stadium and a crowd of 58,753 saw the win over Leverkusen.
After their Champions League heroics in midweek, when they sealed a 12-1 aggregate win over Sporting Lisbon, Bayern Munich lie second in the Bundesliga after experiencing few problems beating ten-man Bochum 3-0 away from home.
After an excellent first-half strike by Brazilian midfielder Ze Roberto after 34 minutes, things got worse for Bochum when French defender Marc Pfertzel was shown a straight red card for hauling down Bayern's Argentina striker Jose Ernesto Sosa when he was clean through on goal.
Lukas Podolski missed the resulting penalty on 48 minutes.
But Bayern extended their lead through a top-class goal from Germany defender Philipp Lahm on 60 minutes after some good work from midfielder Bastian Schweinsteiger - and then Martin Demichelis scored the third on 90 minutes.
Hoffenheim seem to have stalled somewhat, and have now gone six games without a win after they were held to a 1-1 draw at midtable Eintracht Frankfurt.
An early goal by Hoffenheim's Brazilian Carlos Eduardo after ten minutes was cancelled out by a header from Frankfurt's Michael Fink to leave Hoffenheim fourth by now six points off leaders Hertha.
There was a battle royal at Hanover as the home side drew 4-4 with Borussia Dortmund while Borussia Moechengladbach picked up their third win in four games to ease their relegation worries with a 4-2 win at Cologne.
And Karlsruhe are now three points off the pace at the foot of the table after they were beaten 1-0 at home by Arminia Bielefeld.
On Sunday, midtable Werder Bremen host VfB Stuttgart while Hamburg at home to Energie Cottbus.