Born in 1419 as the son of Chiba Kanetane, 16th head of the Chiba clan, Tanenao inherited the family headship in 1430. During the Kyotoku War that split the Kanto region, he initially supported Koga Kubo Ashikaga Shigeuji, but switched allegiance to the Uesugi side when Shigeuji moved to attack them. In response, his uncle Makuwari Yasutane and senior retainer Hara Tanefusa rose in rebellion. In 1455, Tanenao and his brother Taneyoshi took refuge at Shima Castle, which fell under siege; three days after his heir Tanenobu's suicide, Tanenao himself took his own life.

His shift from the Koga Kubo to the Uesugi side amid a conflict splitting the Kanto region appears to have been an agonizing calculation aimed at clan survival. Fighting to the end alongside his brother and heir reflects the pride of a main-line clan head.

Tanenao's death ended the main line of the Chiba clan that had continued since Chiba Tsunetane in the early Kamakura period, and clan leadership passed to the line of Makuwari Yasutane. The Kyotoku War is regarded as a pivotal event marking the onset of the Sengoku period in the Kanto region.