Bugg, 23, was given the double crown for The Albert Dock garden, which was inspired by Liverpool's Albert Dock.
Commenting on his win, Bugg said: "I feel ecstatic, really just amazing."
On going solo from his partner Hallenga, he said: "It's been hard working without her but I'm really pleased that I got this garden completed and won without her; it's fantastic."
Hugo Bugg will go on to help out in the build of the Laurent Perrier garden at Chelsea Flower Show 2011.
"It will be a really good experience next year," he added.
The other finalists - Olivia Stewart (25) and William Quarmby (27) - were awarded joint second and given RHS Silver Gilt medals.
RHS shows director Bob Sweet said: "The three designers had to offer something with an element of the North West; something a little bit different.
"We will soon be launching Young Designer of the Year 2011."
Each of the designers was given £12,OOO to build their garden.