The Magpies agreed a £23m deal with Ajax for the 18-year-old earlier this week, £19.5m of which will be paid in an up-front fee, with Steur flying into the North-East late on Tuesday night.
The teenager completed a medical on Tyneside yesterday and should be officially confirmed as Newcastle’s third summer signing before the weekend.
Steur follows goalkeeper Ewen Jaouen and winger Bazoumana Toure in joining the Magpies this summer, having been withdrawn from Ajax’s training group when Newcastle agreed terms with the Eredivisie club.
Steur has already begun pre-season training with Ajax and played in the opening 45 minutes of the Dutch side’s first friendly of the summer against Panathinaikos last weekend.
READ MORE:
Who Newcastle United will face in three home friendlies - and how to buy tickets
Former Newcastle star lifts the lid on England squad dynamics with revealing insight
While Steur only broke into Ajax’s first-team set-up last season, making 25 senior appearances, he will be given the opportunity to train with Newcastle’s senior group this summer and challenge for a place in Eddie Howe’s matchday squad for the opening game of the Premier League season against Liverpool next month.
Whereas some of Newcastle’s previous teenage signings in the last couple of years have been sent out on an immediate loan move after joining the club, that was never a consideration with Steur.
The youngster is not regarded as a replacement for Sandro Tonali, who joined Tottenham in a £100m over the weekend, but Howe and the rest of Newcastle’s coaching staff do envisage him being involved with the first team on a regular basis next season.
Marijn Beuker, Ajax's sporting director, previously said of Steur: "He is a great talent and has been promoted early for a reason over the past few years. Sean is a dynamic midfielder who can dribble well and always looks for solutions going forward.”