The midfielder left Arsenal after his deal expired at the end of June and new coach Unai Emery could not promise him a place in the first XI.
The Hammers announced the news on Monday afternoon, keeping the England global in the Premier League (and in London) on a three-year deal.
"My family and a few of my friends are West Ham fans so everyone's buzzing".
After 17 years at Arsenal, the 26-year-old has moved on and joined West Ham.
"The fans, of course - everyone knows how big West Ham's fanbase is - and especially in this new Stadium".
Should he avoid any more major injuries in his career, the 26-year-old could be a crucial player in the heart of West Ham's team this season.
"I want to be playing here in front of the Hammers, and my bond I've had with the Club over my childhood will make it even more special".
Liu Xia, widow of dissident, leaves China for Germany, friend says
Friends of Liu Xia had expressed concern for her mental health ahead of the first anniversary of her husband's death on Friday. The widow of Nobel Peace Prize laureate Liu Xiaobo has been allowed to leave China to seek medical treatment in Germany.
Wilshere said there were various factors that influenced him to join the club.
Chelsea FC have joined West Ham United in the race to sign Felipe Anderson from Lazio this summer, according to reports in the Italian media.
He returned to make 38 appearances for the Gunners last season but made a decision to leave in search of first-team football after meeting with new Arsenal manager Unai Emery.
Over the next 10 seasons, he played a total of 125 Premier League games for the Gunners, scoring seven times, with two FA Cup winners' medals to his name.
There were talks of him going to Turkey but Wilshere has chose to stay in the Premier League and sign a three year contract.
Born in Hertfordshire, Wilshere grew up in a family of Irons supporters.
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