The Queens Square shop opened its doors on Friday with ex players Tony Brown and Darren Moore on hand to cut the ribbon.
A crowd of fans gathered to meet the pair and get a first look at possible gifts.
Paul Bradbury, Head of Retail at West Bromwich Albion, said: "It is a really positive move to have an official store here in the heartland of the club's fan base.
"It is something we have considered for a while so when the option came up, and we knew the centre was happy to accommodate us, we snatched at the chance."
The pop-up shop is being leased for three months, as the club aim to make the most of the rush for shirts before Christmas.
It is an addition to the club's store at Merry Hill and the megastore at The Hawthorns.
Mr Bradbury added: "The Christmas jumpers were massive last year and we are expecting them to sell well again.
"On top of that we expect crackers, snowmen and the baubles to be some of the best sellers."
Bosses at Queen Square have said the store is one of four that will be opening in the near future.
And it was recently announced the town's popular market hall in Kings Square will also be getting a six-figure facelift.
Queen Square Centre Manager, Melvin Glasby, hopes the move could be extended.
He said: "If at all possible we would like to see the club stay beyond January.
"It will be down to West Bromwich Albion and ourselves to see if we can come up with an agreement to continue, and if the club feels it would be advantageous to keep this store alongside that at The Hawthorns."
Many of the shoppers who gathered also want the move made permanent.
John Botfild, an East Stand season ticket holder, said: "I'm pleased we've got the shop here now and it's certainly a bit more convenient than having to use the one at the ground."