The 31-year-old, who can operate at fly-half or centre, has won 33 caps for Wales with his last coming in August 2011.
He said: "I am thrilled to be joining Bath this summer, and I look forward to becoming part of what looks a very exciting squad. I still very much want to be playing at the highest level, and Bath is a big club with big plans. I know what is expected of me and I can't wait to get started."
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