But as he starts to recover, Renner has been eager to keep upbeat and has been updating fans throughout the process on social media.
In his latest picture, he can be seen with a physiotherapist working on his leg.
Alongside the snap was the message: "I want to thank EVERYONE for their messages and thoughtfulness. Much love and appreciation to you all.
"These 30 plus broken bones will mend, grow stronger, just like the love and bond with family and friends deepens."
Naturally, it didn't take long for the Avengers to assemble to send their well-wishes.
Chris Evans – who plays Captain America/Steve Rogers in the Marvel series – shared the photo and responded: "That’s one tough mf’er. Has anyone even checked on the snowcat??? Sending so much love."
Renner later shot back: "Love you brother… I did check on the snow cat, she needs fuel," next to a laughing emoji.
Thor actor Chris Hemsworth also shared his support on Instagram, writing: "Your a champion mate! We love you."
Jason Momoa, who stars as Aquaman in the DC Universe, also sent "all his aloha" for Renner's quick recovery.
Renner was rushed to hospital on New Year's Day after getting crushed by the 14,000lb SnowCat while attempting to help someone stuck in the snow near his ranch in Lake Tahoe, Nevada.
He suffered blunt force chest trauma and orthopaedic injuries after the vehicle started rolling and he tried to get back into the driver's seat and fell underneath it.
Renner was airlifted to hospital and thankfully, despite the severe damage, emergency services were able to stablise him and now he can focus on recovery. His family have been by his side throughout.
His sister Kym Renner later told People: "We are so thrilled with his progress. If anyone knows Jeremy, he is a fighter and doesn't mess around. He is crushing all the progress goals. We couldn't feel more positive about the road ahead."
WATCH: Jeremy Renner broke more than 30 bones in snowplough accident on New Year’s Day