Undefeated boxing star Travell Mazion was speeding around a curve when he crossed over the centerline and slammed head-on into oncoming traffic ... this according to the crash report obtained by TMZ Sports.
Mazion -- who was just 24 years old -- was fatally injured in the July 15 wreck in Travis County, Texas at around 9:40 p.m.
In the crash report ... cops say the weather was clear and the road was dry -- but they add it was a dark and not well-lit area.
Officers say in the report, Mazion was speeding as he entered into a curve in the roadway .