The Caltex Socceroos winger smashed home the loose ball seven minutes before half-time after a brilliant advantage was played by debutant female referee Bibiana Steinhaus.
His goal wasn't enough for Hertha as Bremen's Thomas Delaney restored parity mid-way through the second half.
It was Leckie's third goal in three Bundesliga games for Hertha this campaign.
Fellow Socceroo Robbie Kruse was also in the goals, scoring an 86th minute winner for Bochum in their 2-1 win away win at Darmstadt in Bundesliga 2.
Bochum trailed by a single goal with nine minutes to play before Dimitrios Diamantakos struck an equaliser and Kruse secured all three points.
Australian striker Jamie MacLaren was an unused substitute for Darmstadt.