The South Americans got a number of chances to grab the lead, but Gonzalo Higuain, Lionel Messi and Rodrigo Palacio all failed to beat Manuel Neuer before Mario Gotze eventually fired Germany to glory with his goal in the 113th minute.
Hummels was quick to praise the team's work ethic following Germany's fourth world title but conceded the clash at the Maracana could have gone either way.
World Champion...hard to believe... pic.twitter.com/hy8jyVeB17— Mats Hummels (@matshummels) July 14, 2014
"You can only win the World Cup when you act as a team," Hummels told reporters.
"We have tried to make that very clear right from the start and have succeeded in doing so, even if we had our fair share of luck in the final. We were already getting ourselves ready for spot-kicks.
"I am still completely caught up in a different world. I'm physically too exhausted to be able to celebrate euphorically. But it will all sink in in the days to come."