Manchester United's Mata called for high profile players to donate one percent of their wages to charity, and the German international is following his example.
"This is a chance for football to improve our world, and I wanted to be part of it", Hummels said.
Mata wants to create a 'Common Goal starting XI', with 11 players who all donate one percent of their wages to charity.
'He really gets what we're trying to achieve. The fact that a World Cup holder - at the peak of his career with one of the biggest clubs on the planet - has chosen to make the pledge shows the power and magic of what we're doing', Mata said.
Mata came up with the idea in the same week Neymar signed for Paris Saint Germain for a world record fee of £200m.