"I want to publicly thank Arsene [Wenger], the coaching and club staff and my awesome team mates for all the incredible opportunities I have been given".
West Brom did not reveal how much they paid for the 27-year-old, but British media reports put the fee at around £7m.
But the player had his heart set on a move to Liverpool, who beat Arsenal 4-0 in the league on Sunday, and rebuffed Chelsea's advances. Algeria said Mahrez has left the national team to complete a transfer, without naming a club.
New Liverpool winger Alex Oxlade-Chamberlain says his "ongoing development" is the reason why he made a decision to leave Arsenal.
"If you said to me a year ago, or six months ago, you would get £40m for Oxlade-Chamberlain, I would've snapped your hand off."".
Oxlade-Chamberlain may be a good player, but there's a lot to suggest Liverpool fans shouldn't get too excited about their new signing.
Oregon Humane Society team travels to Houston to help animals
The Austin Humane Society said it took in 62 animals over the weekend, sending about 60 animals to foster volunteers. The SPCA contacted local shelters along the coast to let them know they had room for 300 animals, Davies said.
Aaron Ramsey nearly caused controversy when he used #shaambles on social media in response to Arsenal selling Alex Oxlade Chamberlain.
City had reportedly tabled a bid worth up to £60m but Sanchez will now remain at Arsenal with his contract expiring at the end of the season.
For the midfielder to turn his back on both that money and that promise is a damning verdict on Wenger, who clearly failed to make the most of one of England's most talented players. "In the previous year, he has made huge progress and I want him to stay here for a long time".
One player who did land a move away was England worldwide Oxlade-Chamberlain, who completed the formalities on his transfer to Liverpool.
Meanwhile, Ivorian right-back Serge Aurier has joined Tottenham Hotspur from Paris Saint-Germain on a five-year contract, the two clubs announced.
He denied the charge and has appealed against the sentence, which since it is convertible usually results in community service.