De Jong helped his side beat Inter Milan 3-2 to earn the Spanish side's sixth Europa League title in Cologne.
The striker revealed he was a late addition to the starting XI: "It is incredible. We had such tough games all tournament but we played so well as a team.
"We were like a family, we worked together. It didn't matter who came in. It was tough. We started well but they scored out of nothing. Two goals, amazing feeling for me.
"The manager told me this morning (I was starting). I told him I am always ready when he needs me and today it worked really well."
De Jong added on his two headed goals: "I think it is my speciality. The first cross by (Jesus) Navas was perfect, the second was also a great cross and these headers are really special when you can put them in at the near post."