The last time Germany reached the decider in the mixed teams tournament was in 1995, when Boris Becker and Anke Huber gave the country their second title.
The Germans are unbeaten after two ties and Kerber and team mate Alexander Zverev just need to beat the host nation on Friday in their last Group A tie to advance to Saturday's final.
Belgium beat Australia 3-0 in the evening tie on Wednesday and both those teams could sneak into the final if the Germans lose on Friday.
Coming off a frustrating 2017 during which she slid from number one in the world to 21st in the rankings, Kerber is unbeaten in two singles matches in Perth and her confidence is building again.
She easily accounted for struggling Canadian Eugenie Bouchard in straight sets on Wednesday, before Zverev sealed the tie with a similar scoreline against Vasek Pospisil and the Germans wrapped up a clean sweep in the mixed doubles.
Kerber, 29, was bouyant after she notched her second straight-sets win in Perth to start the new year, while Bouchard, once ranked fifth but now 83rd, was testy after yet another comprehensive defeat.
As was the case in her straight-sets loss to Daria Gavrilova on Sunday, Bouchard barely fired a shot against Kerber in the first set but resurrected her game in the second.
At 3-3 in the second set Bouchard held four break points, but Kerber staved them off, held serve and then strolled through the last two games comfortably to win 6-1, 6-3 in 57 minutes.
With emphatic wins over Belgium's Elise Mertens and Bouchard, who had troubled Kerber in previous meetings, the German was thrilled with her early season form ahead of the Australian Open, which provided her maiden Grand Slam in 2016.
“I was feeling very good from the first point,” she said.
“I was trying to be aggressive and play my game.
“It is not so easy to play against Eugenie, but today it was a good match.”
Meanwhile Bouchard could barely contain her frustration, complaining about match scheduling and the off-court activities in Perth after an error-riddled performance.
The 23-year-old said she was trying not to be consumed by the pressure to climb back up the rankings.
“It will take as long as it will take,” she said.
“For me, I can't worry about it, I'm trying to do my best.
“However long it will take is what will happen, and I'll have to deal with that.”
World number four Zverev cruised past the 108th-ranked Pospisil in a 6-4, 6-2 win that the German said was a reward for putting in extra practice after his disappointing singles loss to Belgium's David Goffin on Monday.
The 20-year-old was delighted to have kept his team on track for the final.
“We have two wins now in the group, hopefully we can get one more,” he said.
“It is a team competition and we are in a good spot.”
In the evening tie, Belgians Goffin and Mertens notched their first win and stayed in the hunt for the final by powering past the Australian pairing of Gavrilova and Thanasi Kokkinakis.
The Belgians won both singles matches, with Mertens recovering from a set down to beat Gavrilova 2-6, 6-4, 6-2 and Goffin too good for the promising Kokkinakis 6-4, 6-2.
Belgium plays winless Canada on Friday in their final group tie.