The Greece international, who was a free agent after leaving Celtic earlier this summer, becomes Alan Irvine’s ninth summer signing and he was delighted to have secured the services of the former Manchester City forward.
“We’ve signed a player with vast experience and I’m delighted to welcome Sami to the club,” the Baggies head coach told the club website.
“He has played a lot of football at the highest levels – Champions League, European Championships and World Cups - and the feedback we’ve got on him, from people like Neil Lennon, states he thrives on the big occasion. He will certainly play in plenty of those in the Premier League.
“Georgios has played in big games for a Celtic team that have often had a lot of the ball and have had to work hard to break the opposition down but he has also shown another side to his game in other matches when they haven’t seen as much of the ball.
“We have now got four strikers with different qualities who can be used in different ways. That’s great for us, because we need to have flexibility, the option to approach games in different ways and cover for injuries. I’m absolutely delighted with the four strikers we have.”
Samaras will compete with club-record signing Brown Ideye, Saido Berahino and Victor Anichebe for a place in Irvine’s new-look forward line.
He scored 73 goals in 249 games for Celtic after arriving from Manchester City, initially on loan, in 2008. He was part of Greece's World Cup squad this summer as they confounded the odds to reach the last 16, where they lost out to Costa Rica.