The 24-year-old signed for the Hammers on Thursday, after leaving Ipswich for an undisclosed fee, and is currently training in France with his new team-mates.
"I'm very excited to have signed here," he told West Ham's official website.
"It's a massive club and I can't wait to get ready for the season ahead.
"When I knew West Ham were interested it was an easy decision to make! Everyone knows it's a massive club and a couple of years down the line they'll have the new stadium too.
"It's everyone's ambition to play in the Premier League, and to play in front of 35,000 week in, week out, is a dream come true for me.
"I know we've got Spurs, Man City and Liverpool at home early on and there's no such thing as an easy game in the Premier League, but I'm going to relish every one and hopefully I can play a big part in it.
"If you ask any player in the Football League, they want to play in the Premier League. Some people have to gradually go through the leagues and fortunately for me that's the way it's worked out so I can't wait to get going."
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