Negotiations on a new contract had been held up by changes in the tax law brought about by the recent change in government in Spain and by reported interest from Qatar-owned Ligue 1 side Paris St Germain.
The 32-year-old, a cult figure with Barca fans, joined the Catalan club in 2007 and his existing contract was due to expire at the end of the current campaign.
Abidal had surgery to remove a liver tumour early last year before making a triumphant return to lift the Champions League trophy at Wembley last May.
The former AS Monaco, Lille and Olympique Lyon player has made 177 appearances for Barca and scored just one goal.
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