The Saints confirmed on their official website that the Dutch centre-back has put pen to paper on a five-year deal, and he could make his debut for the club on 12 September against West Bromwich Albion.
— fanatix (@therealfanatix) September 1, 2015
Van Dijk had been rumoured to be on the radar of Arsenal and Manchester United this summer [via the Daily Express], but he has admitted that he was swayed by the ambition at Southampton after completing his move:
“I think it’s the right time for my development,” van Dijk told the club’s website. “I’m still quite young, 24, and still have a lot to learn.
“Southampton is the perfect step for me right now. It’s an amazing club. From the people I’ve met already it’s a very good feeling and I’m delighted to be here.
“I know it’s an ambitious club. They have been through a lot throughout the years. They are trying to play football and that’s something that really attracted me.”
The 24-year-old moved to Celtic in June 2013 from Groningen and made a total of 76 appearances in the Scottish Premiership, and is now set to continue his impressive development in England’s top flight.