Gary Smith, from Clacton, beat competitors from across the world to take the Most Innovative Design award for his "CD Slot Mount".
It fits into the CD player to provide a platform for items such as sat navs, iPods or mobile phones to be put on.
"When they announced it you could have knocked me down with a feather," Mr Smith, 57, said.
"At the show it was amazing because there were people there with some mind-blowing stuff and for them to choose this, which is a simple product, was amazing."
He explained he had spent about two years developing what is his first ever invention.
The idea was sparked when his sat nav was stolen from the dash board of his car and he was looking for a less visible place to put it.
The result was a non-sticky plastic pad on which items can be placed on, which then slots into the front of a car's CD draw.