The attacking midfielder who also plays as a striker has signed a 6 year-deal to play with the English side which would theoretically take him to 31 years of age if he was to stay the entire duration of his contract.
A big player in the move may perhaps have been De Jong's younger brother Luuk who spent the second half of last season at Newcastle on loan from Borussia Monchengladbach but a permanent deal for the young striker was turned down.
The 25 year-old had this to say about his move. "It is great to have signed for Newcastle. It is a big club which my brother told me all about, so I already feel good here."
"I had been at Ajax for a long time and wanted a new challenge in a new environment and a new country."
"Coming to Newcastle is a great opportunity and the chance to play for a club like this in the Premier League was one I could not turn down."
"I am looking forward to starting training and meeting my new teammates and hopefully we can have a successful season."