The two clubs agreed a deal on the final day of the transfer window on Monday and the Spain striker put pen to paper at Stamford Bridge shortly before the 23:00 GMT deadline.
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"I'm sure I am doing one big step forward in my career joining a club like Chelsea," the 26-year-old told Chelsea TV.
"I just want to be at the level I'm supposed to stay. This is a great club, a real responsibility and everyone is expecting great things about me and I'm prepared and ready for the challenge."
"Chelsea are one of the teams I want to play for," Torres, whose 81 goals in 142 games endeared him to Liverpool's fans, said. "They are one of the biggest teams in Europe and after that there is no more steps forward.
"This is the target for me as a player to play for one of the top teams in the world and I have to be very, very happy with that."
Benfica defender David Luiz also joined in a 25 million euro deadline-day deal, boosting manager Carlo Ancelotti's hopes of closing the gap on Manchester United in the Premier League and progressing further in the Champions League.
"Carlo is over the moon," Chelsea chief executive Ron Gourlay said on the club website.
"He did say we needed to bring a couple of players in and I said six months ago if we had to bring someone in then it would be a big signing.
"I'm sure this is great for the team and the morale, and great for the fans who have two major signings to look forward to at Stamford Bridge."
