The 24-year-old New Zealand international has enjoyed a good season alongside James Collins in the heart of the Hammers defence and has featured in all but two of the Premier League matches this season.
His form and consistency since signing from FC Midtjylland in 2010 has lead to another deal and he hopes to continue in the same form he has shown over the past couple of years.
"I've really enjoyed being here," he told the club's official website. "I think I have played some good football over the last two years but that goes for the whole team as well. Hopefully we can continue that."