First-half goals by Julian Draxler and Sami Khedira sealed the win in Hanover as the world champions have yet to concede a goal in their qualifiers for Russia 2018.
Germany have lost just two of 85 World Cup qualifiers in their proud history and were in no mood to give the Northern Irish a first win on German soil for 33 years.
Tears and goals as Keane, Schweinsteiger bow out
With nine qualifying points to their credit, the Germans will finish the year with a perfect record if they next beat minnows San Marino, ranked 198 places below them, away on November 11.
The same night, third-placed Northern Ireland host Azerbaijan, who are second in Group C, in a crunch qualifier.
Germany's head coach Joachim Loew started with the same side which beat the Czech Republic 3-0 in Hamburg on Saturday.
Schweinsteiger, Podolski to play for the last time in Germany friendly
His opposite number Michael O'Neill made three changes to the side which beat 10-man San Marino 4-0 in Belfast, but Kyle Lafferty, who netted twice on Saturday, started again on the bench.
Having been restricted to a 1-0 win when the sides last met, in the group stages of Euro 2016, the Germans raced into a 2-0 lead with less than 20 minutes gone.
Mario Goetze's header tested Irish goalkeeper Michael McGovern early on and Germany took the lead on 13 minutes.
Thomas Mueller laid the ball off for Draxler, who rifled his shot into the bottom right-hand corner.
Despite packing bodies into the penalty area, the Irish defence was again beaten on 17 minutes when Mesut Ozil's cross was headed on by Mats Hummels.Khedira used his head to nudge the ball over the line to make it 2-0.
Goetze then had the ball in the net when he flicked Mueller's pass into the net, but the goal was flagged for offside.
Loew brought on Manchester City's Ilkay Gundogan for Ozil in the attacking midfield role, which seemed to disrupt the Germans' rhythm.
The Irish dug in for the second-half as Germany struggled to make headway through the visitors' dense defence.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ