Officers with the Houston Police Department said the teen was riding with four of his juvenile friends in a Jeep without doors when he took off his seatbelt.
He was reportedly holding onto a strap when it broke, causing him to fall out of the moving Jeep onto the pavement, according to Sgt. David Rose.
First responders transported the 16-year-old to the Texas Children's Hospital in critical condition.
Police say no charges have been filed.