Aomori Prefecture (青森県, Aomori-ken; Japanese pronunciation: [a.oꜜ.mo.ɾʲi, a.o.mo.ɾʲiꜜ.keɴ]) is a prefecture of Japan in the Tōhoku region. The prefecture's capital, largest city, and namesake is the city of Aomori. Aomori is the northernmost prefecture on Japan's main island, Honshu, and is bordered by the Pacific Ocean to the east, Iwate Prefecture to the southeast, Akita Prefecture to the southwest, the Sea of Japan to the west, and Hokkaido across the Tsugaru Strait to the north. Aomori Prefecture is the eighth-largest prefecture, with an area of 9,645.64 km² (3,724.20 sq mi), and the 31st-most populous prefecture, with more than 1.18 million people. Mount Iwaki, an active stratovolcano, is the prefecture's highest point, at 1,624.7 m (5,330 ft).

Humans have inhabited the prefecture for at least 15,000 years, and the oldest evidence of pottery in Japan was discovered at the Jōmon period Ōdai Yamamoto I Site. After centuries of rule by the Nanbu and Tsugaru clans, the prefecture was formed out of the northern part of Mutsu Province during the Meiji Restoration in the 19th century. The entire Tōhoku region, including Aomori Prefecture, experienced significant growth in population and economy until the late 20th century, when a significant population decline began. Though the prefecture remains dominated by primary sector industries, especially apple orchards, it also serves as a transportation and logistics hub due to its location. Additionally, it is the largest producer of black garlic in Japan. Tourism is also a significant part of the prefecture's economy, especially due to the Jōmon Prehistoric Sites in Northern Japan and Shirakami-Sanchi World Heritage Sites.

Aomori Prefecture has a distinctive subculture influenced by its distant location relative to the central government of Japan and the region's long, snowy winters. It is the birthplace of the traditional Tsugaru-jamisen, a local version of the three-stringed musical instrument known as shamisen. Embroidery, pottery, lacquerware, cabinetry, and iron working are also significant crafts in the prefecture. Various porridges and soups are distinctive to Aomori Prefecture. Several festivals are held in Aomori Prefecture; the most noted of which is Aomori Nebuta Matsuri. Aomori Prefecture is home to several association football, baseball, basketball, and ice hockey teams. The prefecture's religious beliefs are heavily rooted in Shinto and Buddhism; it is noted for its blind mediums and purported tomb of Jesus.

The name Aomori (青森) can be literally translated as "green forest". The name was first given to a port settlement established by the Hirosaki Domain in 1624 (modern Aomori City), and most likely originates from a small forest on a hill that existed nearby, which is said to have been used by fishermen as a landmark.

The Jōmon period is the time between c. 14,000 and 300 BCE, during which Japan was inhabited by the Jōmon people, a diverse hunter-gatherer and early agriculturalist population. The oldest evidence of pottery in Japan was found at the Ōdai Yamamoto I Site in the town of Sotogahama in the northwestern part of the prefecture. The relics found there suggest that the Jōmon period began about 15,000 years ago. By 7,000 BCE, fishing cultures had developed along the shores of the prefecture. Around 3,900 BCE, settlement at the Sannai-Maruyama Site in the present-day city of Aomori began. The settlement shows evidence of wide interaction between the site's inhabitants and people from across Jōmon period Japan, including Hokkaido and Kyushu. The settlement of Sannai-Maruyama ended around 2,300 BCE for unknown reasons. Its abandonment was likely due to the population's subsistence economy being unable to result in sustained growth, with its end being spurred on by the reduced amount of natural resources during a neoglaciation. The Jōmon period continued up to 300 BCE in present-day Aomori Prefecture at the Kamegaoka site in the city of Tsugaru where small statuettes called Shakōkidogū have been found.

The Yayoi period, c. 300 BCE – c. 300 AD, is one of the major historical periods of the Japanese archipelago. It is generally defined as the era between the beginning of food production based on rice cultivation in Japan and the emergence of keyhole-shaped burial mounds. The Yayoi people were mostly Chinese immigrants and their descendants. The region, known then as Michinoku, was inhabited by the Emishi. It is not clear if the Emishi were the descendants of the Jōmon people, a group of the Ainu people, or if both the Ainu and Emishi were descended from the Jōmon people. The northernmost tribe of the Emishi that inhabited what would become Aomori Prefecture was known as the Tsugaru. Historic records mention a series of destructive eruptions in 917 from the volcano at Lake Towada. The eruptive activity peaked on August 17. The Heian period, c. 794 and 1185, was characterized by centralized government influenced by China. Throughout this period, the Emishi were slowly subdued by the Imperial Court in Kyoto before being incorporated into Mutsu Province by the Northern Fujiwara around 1094. The Northern Fujiwara continued to rule the Tōhoku region until 1189. Mutsu Province was a large province that was later broken into Fukushima, Miyagi, Iwate, and Aomori Prefectures and the municipalities of Kazuno and Kosaka in Akita Prefecture.

The Northern Fujiwara set up the port settlement of Tosaminato in present-day Goshogawara to develop trade between their lands, Kyoto, and continental Asia. The Northern Fujiwara were deposed in 1189 by Minamoto no Yoritomo, who would go on to establish the Kamakura shogunate, which is known for the emergence of the samurai, the warrior caste, and for the establishment of feudalism in Japan.

The Kamakura period is a phase that marks the governance by the Kamakura shogunate between c. 1185 and 1333. Minamoto no Yoritomo incorporated Mutsu Province into the holdings of the Kamakura shogunate. Nanbu Mitsuyuki, founder of the Nanbu clan, was awarded vast estates in Nukanobu District after he had joined Minamoto no Yoritomo at the Battle of Ishibashiyama in 1180 and the conquest of the Northern Fujiwara.