EXCLUSIVE

50 Cent just went above and beyond to make good with the 19-year-old man he mocked on social media -- he's donated $100,000 to Autism Speaks ... TMZ has learned.

Fiddy referred to the video he posted of Andrew Farrell, saying, "I want to turn this misunderstanding into an understanding. There are people that are ignored, mistreated and neglected with disabilities that need our support."

Farrell's family had asked him to donate $10k to the autism advocacy group -- so ya can't say 50 did the bare minimum in making his mea culpa.