The Mainz forward was on target in the closing stages as the game produced a tremendous conclusion following a rather banal opening
Samuel Eto'o's strike kick started the game after a rather tepid beginning, though when Thomas Muller and Andre Schurrle replied for the hosts it seemed they would claim victory. However, Mainz's Eric Maxim Choupo-Moting found a leveller for the African side.
Coach Joachim Low named a strong XI that included the likes of Marco Reus, Mesut Ozil and Mario Gotze but saw his side struggle to find top gear at Borussia Park.
Cameroon boss Volke Finke will have enjoyed the return to his homeland, where he managed Freiburg for 16 years, although Low and Germany look far from the finished product on the evidence of Sunday's encounter.
The hosts made a lively start and Ozil should have scored within the first minute but could only slip Sami Khedira's pass wide of Charles Itandje's right-hand post.
Itandje then tipped Gotze's strike onto the woodwork before Eto'o, rested for Cameroon's last two friendlies, had the visitors' first effort on target.
However, a number of minor fouls stopped either side from getting into full flow, with the dangerous Reus next to test Itandje before Khedira failed to connect with a cross from the left.
Cameroon could have stolen ahead before the break when Eto'o played in Benjamin Moukandjo, but the Nancy forward saw his prodded effort well saved by Weidenfeller.
Having finished the first half strongest, Cameroon were under threat early in the second half as Reus flashed an effort wide of goal.
However, captain Eto'o, preparing for his fourth World Cup, initially forced a save from Weidenfeller before following up at the second attempt after Choupo-Moting had cut the loose ball back across goal.
Their joy was short-lived, however, as Bayern midfielder Muller headed in the equaliser after good work from clubmate Jerome Boateng on the right. Five minutes later Lukas Podolski, appearing suspiciously offside, broke free down the left and squared for substitute Schurrle to stab the ball home.
However, parity was restored in the 78th minute. Mainz man Choupo-Moting, who was born in Germany, saw his fine goalscoring run continue, finding the net for a third consecutive friendly.
Choupo-Moting broke into the German penalty area from the left to send a low, angled shot beyond Weidenfeller to gain Cameroon a draw and leave Low with a few question marks ahead of Friday's final friendly with Armenia.