The tragic star features alongside singer Kali Uchis on "Time", which was premiered by DJ Zane Lowe on Apple Music's Beats 1 radio station on Wednesday, June 12.
The soulful track is about the ups and downs of a relationship, and on Miller's verse, he offers up some sage advice about a brief separation.
"You get yours, of course, I get mine/And in the end, everything will be fine, that's by design," he raps.
He goes on to spit, "Making the wrong decisions and you sick of it all/But don't leave me, don't leave me/Because it feel too good to be easy, yeah/It's been a while, and I'm even different now/S**t, I'll probably make it better when you see me."
"Time" marks Miller's first posthumous release since suffering a fatal drug overdose in September (18), aged 26.
He had dated Ariana Grande for two years before parting ways in May, 2018.