The defender's switch from Blackburn Rovers was confirmed on Wednesday and, like fellow new arrival Louis Saha, he can't wait to get started.
Ryan has a wealth of experience after seven years at Ewood Park and led New Zealand in the 2010 World Cup in South Africa.
"Looking from afar, it's such an exciting place to be at the moment," said Ryan.
"When I was at Blackburn and looking at the squads, I always thought Tottenham had an amazing squad.
"It's a bit weird, considering I've been trying to kick them for the last eight seasons, but it will be great to play alongside them!"
Ryan joins some high-class central defenders at the club in Ledley King, Michael Dawson, Younes Kaboul and William Gallas.
"They are all world-class players," added Ryan.
"I know my role and why Harry's brought me in so if I can help out and contribute in any way, that will be fantastic.
"All I know is that I'm delighted to be here and I will work my socks off. I'll give everything for this club."