Zach Miller -- the Chicago Bears tight end who nearly lost his leg in 2017 after suffering a horrific injury -- says he's done with football ... announcing, "The time has come."
Miller severely mangled his leg during an Oct. 29, 2017 game against the New Orleans Saints ... when his left knee snapped as he tried to haul in a TD pass in the 3rd quarter.
The injury was gruesome ... his knee dislocated so severely that vascular surgeons were called in to help repair a damaged artery.
You can watch the video here .