The 22-year-old, capped eight times for Trinidad and Tobago, suffered a heart attack after a training session in Budapest on 25 September.
He had been hospitalised since and underwent three operations, having his left leg amputated to alleviate circulatory problems. Adams had been awaiting a heart transplant. "We have the painful task of announcing the death of our Trinidad and Tobago player, Akeem Adams on December 30," his club said on its website.
Adams signed for Ferencvaros last summer and had played six matches for his new club.
The Trinidad and Tobago Football Association (TTFA) said it was "deeply saddened" by news of Adams' death. It quoted his uncle, Ivan Dick, saying: "He went on his own. This was God's call. He is at peace now. We wish to thank all of those who offered their support to Akeem and his family. He touched us all in so many ways."
TTFA president Raymond Tim Kee said on the association's website: "No words can fully express our grief and dismay on what has happened. Everyone in our football fraternity is deeply affected by this. Not only was he a promising and dedicated footballer, but he was also a fine young man."