Shimazu was the overseer of the Tenpō Reforms under Zusho Hirosato and an initiator of the Kaei purge.

In June 1809, his father, Yoshinobu, was forced into retirement by his grandfather, Shimazu Shigego, in order to take responsibility for the collapse of the Kinshiroku, so he took over the headship of the clan and became the 10th lord of the domain.

Under the leadership of the Census Bureau, the administrative reforms of the domain had great effects, such as paying debts in 250-year installments, smuggling trade with the Qing Dynasty, monopolizing sugar, and making counterfeit money, and the finances of the Satsuma domain quickly recovered.

Shimazu Nariakira canceled his planned military expedition to Kyoto and refused to protect Gessho, who had fled from Kyoto to Satsuma during the Ansei era, he hid Saigo Takamori's identity on Amami Oshima, and informed the shogunate of Saigo's death.

He also carried out restoration policies such as ordering the reduction of the Shuseikan, but died of illness on September 12, 1859.