Germany deservedly topped Group B to set up a last four meeting with Mexico at the same venue on Thursday after the first global goals for Kerem Demirbay and Timo Werner, who got two.
Germany looked set for a comfortable win although Cameroon to their credit stuck to their task despite the numerical disadvantage, and pulled a goal back when Aboubakar headed home on 79 minutes.
Neither were in evidence Sunday in Sochi as Cameroon defender Ernest Mabouka eventually left the field around three minutes after his boot connected with Emre Can of Germany.
As Group B winners, the Germans will face Mexico in the semi-finals in Sochi.
Australia needed to win by two goals to advance to the semifinals, which put the possibility of a stunning upset very much in play, as did the Socceroos' rough-and-tumble tactics. They will meet Mexico.
Ter Stegen prevented Cameroon going in front, with the goalkeeper's one-handed save blocking Andre-Frank Zambo Anguissa's hooked shot across goal at the end of a nervy first-half for the Germans.
Cameroon, Australia hopes hit after 1-1 draw
The game was like the show 24: entertaining, violent, fast-paced and utterly meaningless in the grand scheme of things. A neat pass behind Bailey Wright saw Cameroon hit the byline, target man Vincent Aboubakar waiting for the cut back.
Then came the red-card confusion, swiftly followed by Germany's second goal.
Demirbay and Werner's goals were their first at global level and Low added: "Players are always motivated and have developed a lot in recent years".
"Thanks also to the players, those players who were perhaps not here with us today who played a lot in the past or just a few matches".
Low said the undoubted highlight of his 11-year spell in charge - he took over from Jurgen Klinsmann in July 2006 - was the 7-1 thrashing of hosts Brazil in the semifinals of the 2014 World Cup.
Cameroon were gifted a way back into the match when Marc-Andre ter Stegen let Aboubakar's header burst through his gloves in what was a poor goal to concede for the Barcelona keeper.
The Colombian official arrived at what was arguably the correct decision following two visits to the touchline to consult video replays and first showing only a yellow card, then a red card, to the wrong Cameroon player.
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