The Canadian born star, who has been open with his disapproval of Trump in the past, has taken his disdain a step further, branding him a "disgrace" in a letter posted on his Neil Young Archives website.
"You are a disgrace to my country," he writes. "Your mindless destruction of our shared natural resources, our environment, and our relationships with friends around the world is unforgivable... Our first black president (Barack Obama) was a better man than you are... I hope you hear my voice. Remember it is the voice of a tax-paying U.S. citizen who does not support you."
Young also addressed Trump's use of his track "Rockin' in the Free World", urging him to refrain from playing the track at his rallies.
"(It) is not a song you can trot out at one of your rallies," he adds. "Perhaps you could have been a bass player and played in a rock & roll band. That way you could have been onstage at a rally every night in front of your fans, if you were any good."
Trump previously revealed he's a fan of the Canadian musician in a 2008 interview with Rolling Stone.
"He's got something very special," Trump told the publication.