On 1526, Takahisa was adopted as the successor to Shimazu Katsuhisa and became head of the clan. He launched a series of campaigns to reclaim three provinces: Satsuma, Osumi, and Hyūga. While he made some progress, it would be up to the next generation in the Shimazu family to successfully reclaim them. He nurtured such future leaders like Shimazu Yoshihisa and his brothers Yoshihiro, Toshihisa and Iehisa who would, for a short time, see the Shimazu clan take over the entire island of Kyūshū; he is also said to have a daughter of unknown name.
Takahisa actively promoted relationships with foreign people and countries. He was the first daimyo to bring Western firearms into Japan, following the shipwreck of a number of Portuguese on Tanegashima in 1543. In 1549, he welcomed St. Francis Xavier. He granted the Jesuit protection to spread Christianity in his domain, but later retracted his support of Christianity under pressure from local Buddhist monks. Takahisa also held a diplomatic relationship with the Ryūkyū Kingdom.
- Frédéric, Louis (2002). Japan Encyclopedia. Cambridge, Massachusetts: Harvard University Press.