The 33-year-old, who has been capped 95 times by his country and been on two British and Irish Lions tours, left Ospreys after 11 years at the end of last season.
He had been expected to rejoin them once the dispute between the Welsh Rugby Union and the four Welsh regions had been settled, but Jones has instead joined the capital outfit.
He wrote on Twitter: "Delighted to have signed for the @cardiff_blues - exciting times! Loved every minute playing for the @ospreys the last 11 years - it's been ace!"
Jones has been training with boyhood club Neath to maintain his fitness while his future has been in limbo.