Speculation has raged for weeks over the player's future and fuel was added to the fire recently when he left his accommodation in Preston.
The Jamaica international turned down a lucrative contract extension earlier this year and will be able to leave Deepdale on a free next summer.
Preston chairman Derek Shaw told the official club website: "We have to be realistic. There is no point holding on to a player who is not 110% behind the club and his team-mates. My job as chairman is to secure the best deal for the club."
Shaw claims Fuller has been unsettled since Preston rejected a bid from Wolves earlier this year, while the Baggies are actively seeking to sign a new striker ahead of their forthcoming Premiership campaign.
Lilywhites boss Craig Brown admits it is a blow to his plans for the Championship campaign and said: "I am naturally very disappointed.
"Apparently Ricardo is very impatient to get into the bigger money. It is a blow to lose one of the better players, but we will press on as a matter of urgency to find a suitable replacement."