Endō Tanetoshi served as a bushō during the Sengoku period. He was the lord of Kigoe Castle in the Gujō District of Mino Province.
Tanetoshi was born as the eldest son of Endō Taneyori.
On 8/1 of Eiroku 2 (1559), Taneyori was assassinated by Tō Tsunetaka, the eldest son and designated heir of Tō Tsuneyoshi. As a result, Tanetoshi succeeded his father at an early age. Initially, his grandfather, Endō Taneyoshi, appears to have served as the guardian for Tanetoshi. Later that same month, his uncle, Endō Morikazu, decimated the Tō clan and became the lord of Hachiman Castle. During the Eiroku era (1558 to 1570), Tanetoshi was allocated territory in the northwest portion of the Gujō District. According to a letter from Saitō Yoshitatsu dated 8/14 of Eiroku 2 (1559), Tanetoshi, along with Morikazu, were ordered to adjudicate political matters in the Gujō District. After one-half of the territory allocated to Tanetoshi was from Morikazu, they were referred to as the Ryō-Endō, or two Endō families.
In 1562, Morikazu died and was succeeded by his thirteen-year-old son, Endō Yoshitaka. In 1564, Tanetoshi took advantage of the capture by Takenaka Shigeharu (Hanbei) of Inabayama Castle by attacking and garnering control of Hachiman Castle. Yoshitaka, however, entered Kariyasu Castle to resist. In 1564, after acquiring reinforcements from his stepfather, Nagai Michitoshi, Tanetoshi settled with Yoshitaka and was able to return to Hachiman Castle.
In 1567, after Oda Nobunaga topped Inabayama Castle, Tanetoshi and the main branch of the Endō led by Yoshitaka appear to have submitted to Nobunaga. On 5/25 of Genki 1 (1570), Tanetoshi was ordered by Nobunaga to deploy to Gifu. Together with Yoshitaka, he served under the command of the Oda army, participating in battles against the allied force of the Azai and the Asakura to the south of Yokoyama Castle. In the eleventh month of the same year, under Sakai Masahisa, Tanetoshi and Yoshitaka guarded Katata, but, on 11/26, were attacked by the Azai and Asakura forces, and, along with Masahisa, were killed in action in an event known as the Siege of Shiga.
Tanetoshi was succeeded by his younger brother, Endō Tanemoto.