The X Factor twins beat four other acts on The Late Late Show Eurosong Special after securing the most public votes and regional jury votes with their track 'Waterline'.
They will now represent their country in Azerbaijan on May 26, after coming eighth in Düsseldorf last year with their song 'Lipstick'.
Jedward said following their win: "It's crazy. Oh my God, we are so excited.
"We did it last year, we're going back and we have so many fans all across Europe. It's going to be, like, we are back, return of the Jedward."
The Celebrity Big Brother stars dominated European music charts following their 2011 Eurovision appearance, selling 120,000 copies of 'Lipstick' in Sweden alone.
Jedward recently landed their own Channel 5 home video series called Weird Wild World.
Watch Jedward performing 'Waterline' on The Late Late Show Eurosong Special below: