Miller wrote about his retirement on Instagram:
To the city of Chicago, my beloved bears fans and NFL fans everywhere... The time has come to move on from playing the game of football. It has been an incredible journey for myself and my entire family and we can't thank you enough for your continued support. I would love more than anything to step on Soldier Field one last time but I physically cannot give the game and our fans what they deserve. It's difficult to find words to express my love and gratitude to every single person that has cheered my name, picked me up and stood strong with me throughout my time in this league. I am forever grateful.
To the McCaskey Family and the entire Bears organization, THANK YOU for changing my life! To my Family, teammates and coaches, I value nothing more than the friendships and love I have gained from this game! I love you all!
And to everyone else chasing a dream... never stop, never settle!
Miller, 34, dislocated his left knee and tore his popliteal artery when attempting to make a touchdown reception. The injury was so severe his leg was nearly amputated, but doctors were able to save it with vascular surgery and several subsequent procedures.
The Bears signed him to a one-year contract last June, knowing he would not be able to play during the 2018 season. The contract allowed him to continue using the Bears' rehabilitation facilities and covered him under the league's medical insurance plan.
Miller had said his eventual goal was to return to the field, but it appears his leg did not heal enough to make that a reality. Given the scariness of Miller's injury when it happened, the fact that he can walk on his own power is a win in and of itself.
Miller recorded 146 receptions for 1,631 yards and 15 touchdowns during his NFL career.