Aoyama Yoshitsugu was born in Owari Province and the son of Aoyama Nobumasa, a retainer of Oda Nobuhide and guardian of Oda Nobunaga. Yoshitsugu was an ancestor of the Aoyama family associated with the Kaga domain during the Edo period.  He served from the age of fifteen as a retainer for Oda Nobunaga. Yoshitsugu later served the Maeda clan and wed Chōjuin, the adopted daughter of Maeda Toshinaga.  In 1575, he earned recognition for his achievements on the battlefield as a member of twenty-one bushō from Fuchū in Echizen Province and was awarded a fief of 1,000 koku.  In 1583, his domain expanded 2,000 more koku for contributions on behalf of Maeda Toshinaga at the Battle of Shizugatake.  Thereafter, he supported Maeda Toshiie in further conflicts including the Siege of Suemori Castle and the Siege of Hachiōji Castle.  He became the chief commander to protect Jōno Castle and lord of Uozu Castle in Etchū Province, acquiring a domain of 17,000 koku.

During military campaigns on the Korean Peninsula known as the Bunroku-Keichō Campaign that occurred in two phases from 1592-93 and from 1597-98 during the reign of Toyotomi Hideyoshi, Yoshitsugu continued to serve under Maeda Toshiie and went to Hizen Province. In 1598, he was awarded the court titles of Junior Fifth Rank (Lower) and Governor of Sado.

In 1600, Yoshitsugu defended Kanazawa Castle in the Siege of Daishōji Castle in Kaga Province.  He died in Uozu in 1612 and was succeeded by his son-in-law, Aoyama Nagamasa.