Asano Yoshinaga was born at Odani, in the Asai district of Ōmi Province, in 1576, the eldest son of Asano Nagamasa. Nagamasa was the adopted brother of O-Ne, Toyotomi Hideyoshi's wife. His first action was at the Siege of Odawara, in 1590. In 1593, together with his father, he was granted Fuchu, in Kai Province. Though the Asano family was to be sent to Noto Province as a result of their implication in the alleged treason of Toyotomi Hidetsugu, the good offices of Maeda Toshiie kept them in Kai Province.
Yoshinaga achieved distinction together with his father in 1597, during the Siege of Ulsan, when they held the fortress under the command of Kato Kiyomasa. Though the Asano family was secure following its service under Tokugawa Ieyasu at the Battle of Sekigahara, it would be moved to Wakayama han, in Kii Province (The family would again be moved, this time to Hiroshima han, in the early 1600s).
Yoshinaga's three-dimensional battle standard, a gold-plated basketlike object, was well-known during the Korean campaign.