"I've got good memories of my childhood supporting West Ham, watching them at Upton Park".
"It feels special", the 26-year-old told West Ham's website.
The midfielder grew up supporting West Ham and while it would have presumably been a hard decision to end his 17-year association with Arsenal, moving on is what's best for his playing career. He will join up with Pellegrini's squad for their pre-season training camp in Switzerland.More news: Shearer: "The Third and Fourth Place Play-Off is utter stupidity"
"Jack Wilshere is a playmaker", Wenger said.
"I had all the shirts, my brother did, I think I had John Moncur on the back of that, you know". "The manager [convinced me],..."
"The fans, of course - everyone knows how big West Ham's fanbase is - and especially in this new Stadium". Not many clubs could fill it week in, week out, and West Ham do.
Meanwhile, NAIJ.com had earlier reported Jack Wilshere has confirmed he will quit Arsenal once his current contract with the club expires at the end of this month.More news: HBO's 'Game of Thrones' leads nominations for television's Emmy awards
After a fight against relegation and a season marred by crowd trouble, West Ham's owners pledged to plough money into the club in order to improve the squad and make the Hammers contenders for a top seven place.
Wilshere made his senior debut for Arsenal in 2008, going on to make 197 appearances and winning the FA Cup twice - in 2014 and 2015.
Manuel Pellegrini seems intent to bolster West Ham's attack this summer with Anderson looking set to follow Borussia Dortmund's Andriy Yarmolenko to the London Stadium, after the Hammers agreed a fee of £17.5m for the Ukraine worldwide earlier this week.More news: U.S. ramps up trade row with China, threatens new tariffs