Wagg, now 17, chalks it up to good luck.
"It is very difficult to do, no matter how good you are at actually looking for them," he told the BBC. "In a way, some of it comes down to luck. Just finding it ... you can be as good as you want and still never find one."
So maybe there's hope for the rest of us.
Wagg's planet has been given the catalog number WASP-142b. It orbits a star in our galaxy about 1,000 light years away -- too distant to obtain a direct image.
According to the university, the planet is about the size of Jupiter but orbits its star in about two days, making it much easier to find.
The sun-facing hemisphere is hot and gassy from the radiation coming from its star, while the other hemisphere is cooler.
Wagg used data collected from the Wide Angle Search for Planets (WASP), which scans the skies to look for those dips in light that signal an orbiting planet.
"The WASP software was impressive, enabling me to search through hundreds of different stars, looking for ones that have a planet,'' Wagg said in a statement.
"It looks boring, but when you think about what you're actually doing it's amazing really," he added to the BBC.
Wagg is, unsurprisingly, a straight-A student and plans to study physics. A paper analyzing his planet is currently in the works.