The letter, which was uploaded on Scribd via the New York Post, finds 6ix9ine (real name Daniel Hernandez) apologizing for his actions and reflecting on his life while he has been incarcerated.
"I find it difficult to find the right words to express what my life has been like for the last year," the rapper said in his letter. "It honestly feels like my world is crashing down."
"There is no excuse, no justification and no apology good enough in this world to explain my crimes," the rapper also wrote. "While I have been incarcerated, I have had time to reflect on the recklessness and foolishness of my decisions. I wake up every morning asking myself was it worth it?"
Elsewhere in the letter, 6ix9ine said he felt relief when authorities arrested him because, "I felt stuck, like the gang had control of my life and that I would never be able to escape their grip. I needed to do something before it was too late."
Previously, prosecutors recommended a lighter sentence for 6ix9ine after he testified against his Nine Trey crew.
Last November, Tekashi was arrested for numerous racketeering, firearms, and drug charges. By February he had pleaded guilty to nine charges. At that point — before he became a government informant — he was facing a minimum sentence of 47 years in prison.