The 30-year-old, who will link up with former team-mate Danny Murphy at Ewood Park, has signed a four-year deal with the club.
Etuhu made 127 appearances for the Cottagers including in the 2010 Europa League Final defeat to Atlético Madrid.
The midfielder becomes Steve Kean's seventh signing of the summer as he looks to rebuild his team that was relegated from the Premier League last season.
The Scot is delighted to have secured the signature of Etuhu, and feels he will bring a lot of quality to the Rovers squad.
He told the club's official website: "Dickson is a player I have admired for a long time and he will be a fantastic addition to the squad.
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