"I always wanted to be a footballer as a kid, but also to play for Liverpool," Keane, who has penned a four-year Reds deal, said. "I've been waiting for this day since I was a kid. Everyone knows I am a massive Liverpool fan, so to be sitting here today in a Liverpool tracksuit is a dream come true.
"Now I am enjoying every minute and I can't wait to pull on that red shirt. This is a massive club and want to do everything I can to make them even more successful. The reasons I left Spurs are that I am a huge Liverpool fan and the chance to play for them may never come around again. This opportunity is something I couldn't let go.
"I do not think I let Spurs down. I had six fantastic seasons there and gave them everything since day one. I always give everything, and that will never change.
"The Spurs fans were magnificent to me and I will always have a place in my heart for them. But this is a new chapter in my life and one that I am looking forward to."
Keane has been handed the No 7 shirt, famously worn by Kenny Dalglish and Kevin Keegan, and the former Leeds United forward says he understands the weight of responsibility that comes with it.
Keane says he is also relishing the prospect of playing alongside Fernando Torres, who he describes as "the best striker in the world". "He has been a revelation since he came to the Premier League," Keane said. "He was absolutely outstanding last year and also in Euro 2008 with Spain.
"It is hard to leave Tottenham with some of the players they had - like Dimitar Berbatov, who I had a great relationship with - but Torres is probably the best striker in the world right now. Hopefully we can play a lot of games together and do well."
Keane says he fully expects to be judged on the number of goals he scores but expects to play just off Torres in the Liverpool formation. "I see myself as a second striker," he said.
"I can play off the shoulder, link things up and play in the hole. You are always judged on scoring goals as a striker and I have always scored a lot of goals. Hopefully I can continue that.
Rafael Benitez, the club's manager, was delighted to have completed the signing. "We were looking for a player with game intelligence and good movement who could play alongside Torres," he said. "He can play with Torres up front and also on the right.
"He is a player who can give to us a lot of goals - normally he gets about 15 each year. We were looking for the workrate he can give to us and the goals."