Jimi Heselden, who's company purchased Segway, was driving an off-road version of the vehicle down a trail on his North Yorkshire property when it fell off a cliff and into the Wharfe, reports The Telegraph.
"At this time we do not believe the death to be suspicious," a police statement provided to the newspaper said.
His body was reportedly discovered by a passerby, and police say his Segway was recovered from the river.
Heselden earned his millions (he was reportedly worth about $263 million) by inventing a barrier system using a cage filled with sand and water that sold in huge numbers to the U.S. and British militaries, and NATO.
The HESCO Bastions are effective at stopping bullets, other ammunition and artillery and vehicles and are widely used in both Iraq and Afghanistan.
Heselden founded that company with his severance pay after being laid off as a miner.