The 21-year-old joins the Dutch Eredivisie side, after his first taste of senior action during a loan spell with Northampton Town in 2018/19.
Under-23 coach Simon Rusk said, “This represents a fantastic opportunity for George, who has progressed very well at the club since joining us at the age of 11.
“He has worked exceptionally hard to overcome a couple of big injury setbacks in the last year, and thoroughly deserves this chance in the Dutch top-flight.
“On behalf of everyone at the club, I would like to wish him well for the season ahead. We will be watching his progress with interest, but the long-term aim for him is to make the move permanent.”
Cox was a mainstay in the Albion under-23 side that achieved promotion to Premier League 2 Division 1 in 2017/18, featuring in all 24 league and play-off matches.