According to "Genpei Seisuiki," Tamemori went to the front together with his elder brother TAIRA no Yasumori to hunt down Kumano area in October 1180; in 1182, he was appointed to the general in charge of the Nankaido area under the plan of hunting down various provinces (the plan was not executed); he died in the battle by being struck his head by Kanemitsu HIGUCHI, the commanding officer of Yoshinaka KISO, on June 10, 1183, during the Battle of the Kurihara Pass.
兄平保盛と共に同年9月には熊野討伐に出陣し、寿永元年（1182年）には諸国追討計画（未実施）で南海道方面大将に任ぜられるが、寿永2年（1183年）5月12日、倶利伽羅峠の戦いで木曽義仲の部将樋口兼光に首をはねられ討死したと『源平盛衰記』には記されている。