Hara Nagayori served as a bushō during the Sengoku and Azuchi-Momoyama periods.

Initially, Nagayroi served Oda Nobunaga and was the lord of 花木 Castle (also known as Nakano Castle) in the Motosu District of Mino Province.  In 1575, Nobunaga led his army into Echizen Province in a bid to subjugate the Echizen Ikkō-ikki. Nagayori, along with Kanamori Nagachika and others invaded from Oku-Hida (the Takahara River basin in the northern part of Hida) to Oku-Echizen and mopped up the Ikki forces.  After the battle, Nobunaga awarded Nagayori one-third of the Ōno District in Echizen totaling 20,000 koku.  Nagayori joined the military forces commanded by Shibata Katsuie and became the lord of Katsuyama Castle.  In 1578, after Araki Murashige revolted against Nobunaga, Nagayori contributed to the military effort to subdue him.  In 1579, upon orders of Nobunaga, he was in charge of the execution of the Araki family after the Siege of Arioka Castle.

After the demise of Nobunaga in the Honnō Temple Incident on 6/2 of 1582, Nagayori served Katsuie, joining the vanguard at the Battle of Shizugatake in 1583, and, while the army fled in defeat, served in the rear guard.  Later, he abandoned Katsuie in favor of Hashiba Hideyoshi.  After the conflict, Nagayori joined Tokuyama Hideaki (Shūgen) to serve under Maeda Toshiie and, in 1584, made contributions at the Battle of Noto-Suemori Castle.  In 1585, as a direct retainer of Toyotomi Hideyoshi, Nagayori was awarded a fief of 30,000 koku in Ise Province.  In 1590, after the Conquest of Odawara, Nagayori was transferred to Mikawa.  In 1598, he was then transferred to Ōtayama in Mino Province.

In 1600, at the Battle of Sekigahara, Nagayori affiliated with the Western Army, leading 800 soldiers in an attack against Nagashima Castle in Ise defended by Fukushima Takaharu.  Nagayori recommended to Ishida Mitsunari to invade Owari from Ise and attack Kiyosu Castle, and Mōri Motonari agreed, but Mitsunari was opposed to the plan so it was not carried out.  Although Nagayori intended to participate in the main clash at Sekigahara, upon hearing that the Western Army lost, he fled and, on 10/13, killed himself.  He was fifty-seven years old.

His son, Hikosaku, served Inaba Norimichi, the lord of the Bungo-Usuki domain in the Edo period, but, during the Siege of Ōsaka, he was caught attempting to side with Toyotomi Hideyori and was executed.