Tudor Manolache, from Luton, was riding the vehicle along the pavement of Hatters Way in Luton on September 5 last year when he collided with 88-year-old Leonard Bailey who was walking in the opposite direction.
Mr Bailey was taken to hospital and died of his injuries a few weeks later.
It was estimated that the 39-year-old was travelling at between 20 to 30 miles per hour on a Begode RS, a single-wheel electric vehicle, when the incident occurred.
Manolache was sentenced at Luton Crown Court to 14 months in prison on Friday having pleaded guilty to causing death by careless driving and causing death whilst uninsured or unlicenced.
He will also be disqualified from driving for two years, with the ban set to start as soon as he is released from prison.
Detective Sergeant David Burstow, from the Bedfordshire, Cambridgeshire and Hertfordshire serious collisions unit, said: “This is a precedential case as it is the first prosecution in our area resulting from a fatal collision involving a personal light electric vehicle.
“As the vehicle was propelled solely by an electric motor, it is classified as a motor vehicle which means it requires the same documentation as a car in order to be ridden on a road or public place.
“Manolache has taken full responsibility and is very remorseful for causing the collision which led to the sad death of Mr Bailey.
“Our thoughts remain with Mr Bailey’s family and friends.
“I want to take this opportunity to remind people that use of a personal light electric vehicle such as this, or the more common two-wheel scooter, is illegal on the road or a public place, except in official trial areas on trial vehicles.
“Even then, use on the footpath remains illegal, owing to the increased risk to pedestrians.”
To operate an electric unicycle, the rider stands on it and leans in order to accelerate, brake and steer.