After a forgettable goalless first half at the Olympiastadion, which was once again without fans in attendance as Germany's top flight began its second weekend back following the enforced hiatus due to the coronavirus pandemic, captain Ibisevic emphatically headed home Marvin Plattenhardt's left-wing cross in the 51st minute.
Hertha came under fire for their close-proximity celebrations in last week's 3-0 win at Hoffenheim and Ibisevic told his team-mates to mark his goal with socially-distant congratulations, though he did plant a playful headbutt on the chest of Dedryck Boyota, who denied he kissed Marko Grujic on the cheek in the Hoffenheim win.
Just 69 seconds after his goal, Ibisevic played in Lukebakio and he coolly rounded the on-rushing Rafal Gikiewicz before sliding into the empty goal.
A fine outing for Ibisevic continued when he teed up Matheus Cunha, scorer for a fourth Bundesliga game in succession, to brilliantly side-foot into the bottom-right corner from the edge of the box.
Union's misery was compounded when Boyata headed home Plattenhard's corner with 13 minutes to go.
The win saw Hertha move up to 10th, while Union were two places and four points back.