Amy Van Dyken -- I'M WALKING ... With Bionic Legs!

U.S. Olympic hero Amy Van Dyken IS WALKING AGAIN ... just two months after severing her spinal cord in an ATV accident ... all thanks to some incredible medical technology.

The gold medal winning swimmer was unable to move her legs after crashing an ATV in Arizona on June 6th ... but doctors have equipped her with an Indego exoskeleton and today she posted video taking her first steps.

It's pretty damn incredible ... considering Amy's situation was so bad, doctors told her there was a chance she could have died in the emergency surgery following the accident.

Amazing.