The Irish popstar had been selected to represent Ireland but failed to make it to this weekend's final after being eliminated during last night's semi-final in Stockholm.
18 acts had competed for the last ten spots.
A disappointed Nicky tweeted afterwards: "Amazing Time. Amazing Support. I gave it my all, I'm sorry I didn't get us there. I pass on the torch to someone else now next year."
Nicky, 37, had performed a song called 'Sunlight', which he co-wrote with songwriter Wayne Hector and composer Ronan Hardiman.
In a change to how Ireland selected its Eurovision contestant, Nicky was picked by broadcaster RTE rather than allowing the public to vote.
Speaking earlier this year, he said: "Like many of us, I have grown up watching the Eurovision Song Contest. It always brought great excitement to our house down through the years and I was lucky enough to see Ireland win it on many occasions.
"I have a great memory as a nine year old, of dancing around our sitting room in a tri-colour sweatshirt when Johnny Logan lifted the trophy in 1987. The Eurovision is a TV show and song contest like no other and for the past three years my Eurovision experience has gotten better and my affiliation grown stronger, as I have proudly delivered the Irish votes live from Dublin."
The UK automatically qualified for the final as one of the 'big five' countries alongside France, Germany, Italy and Spain. The UK's act is duo Joe and Jake.
Eurovision airs Saturday,14 May at 8pm on BBC One.