Mamadou Niang, Kader Keita, Ibrahim Abdulmajed, Hasan Al Haydos and Nadir Belhadj converted their penalties to give the Qatar side victory.
Kashiwa’s Ryohei Hayashi missed his attempt in the third round of the shootout and Belhadj sealed the triumph by driving past Kashiwa goalkeeper Takanori Sugeno in the final round.
The match was a tepid affair that ended 0-0 with neither side able to generate much of an attack.
Kashiwa qualified for the competition as the J-League champions, while Al-Sadd entered as the winners of the Asian Champions League.
Barcelona will play Santos of Brazil in the Club World Cup final later Sunday.
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