The 30-year-old had been heavily linked with a move to Stamford Bridge and he joins the Blues on a three-year deal.
He told the club website: 'I am very excited to come to a club like Chelsea, it is a big club and I think it is a dream for every player. Hopefully we will be successful."
Benayoun, who has moved for an undisclosed fee, first moved to the Premier League in 2005 when he joined West Ham from Racing Santander.
His excellent form for the Hammers, for whom he played in the 2006 FA Cup final, saw him secure a move to Anfield in the summer of 2007.
He made 134 appearances for the Reds and scored 29 goals, including the header that gave the Merseysiders a 1-0 win at the Bernabeu when they met Real Madrid in the last 16 of the Champions League during the 2008-09 season.
Blues boss Carlo Ancelotti hopes the addition of Benayoun will help his side retain the Premier League title and finally secure Champions League glory.
The Italian said: "We are happy to have this new player. Yossi has a lot of quality in midfield and can play in lots of positions. I like his behaviour on the pitch and he will do a great job for us next season."
A Liverpool spokesman, confirming the move on the club website, said: "Yossi's departure was agreed between the player and (former manager) Rafael Benitez a number of weeks ago. Everybody at Liverpool FC wishes him well for the future."