The Holland Under-21 international, the Baggies' fifth summer capture as they prepare for life back in the Barclays Premier League, joins from Dutch club Heerenveen, who revealed the move yesterday.

Zuiverloon scored the winning penalty in an epic semi-final shootout against England at last year's UEFA European Under-21 Championship and is set to play for his country at the Olympics.

West Brom also have the option of extending his contract for a further year.

Manager Tony Mowbray said: "Gianni is a player that originally came to my attention during pre-season last year when we played Heerenveen.

"We've followed his progress throughout the season and I'm delighted he has agreed to join us.

"From our point of view, we've got a very talented, young footballer who is eager to prove his qualities at the highest level.

"He has good defensive qualities, is a good athlete, is comfortable on the ball and wants to improve.

"He will add good competition for places to the squad and is another piece in the jigsaw.

"Hopefully he is the first of a few new signings to come in as we continually look to improve the squad."

The Baggies have now spent almost £10million this summer following the permanent captures of Roman Bednar, Luke Moore, Kim Do-Heon and Graham Dorrans.