Arusha Region (Swahili: Mkoa wa Arusha) is one of Tanzania’s 31 administrative regions and is located in the north of the country. The region’s capital and largest city is the city of Arusha. The region is bordered by Kajiado County and Narok County in Kenya to the north, the Kilimanjaro Region to the east, the Manyara and Singida Regions to the south, and the Mara and Simiyu regions to the west. Arusha Region is home to Ngorongoro Conservation Area, a UNESCO World Heritage Site. The region is comparable in size to the combined land and water areas of the state of Maryland in the United States.

Arusha Region is a tourist destination in Africa and is the hub of the northern Tanzania safari circuit. The national parks and nature reserves in this region include Ngorongoro Conservation Area, Arusha National Park, the Loliondo Game Controlled Area, and part of Lake Manyara National Park. Remains of 600-year-old stone structures are found at Engaruka, just off the dirt road between Mto wa Mbu and Lake Natron. With a HDI of 0.721, Arusha is one among the most developed regions of Tanzania.

The Great Rift Valley runs through the middle of the region north-to-south. Oldonyo Lengai (Mountain of God in the Maasai language) is an active volcano to the north of the Ngorongoro Conservation Area. Altitudes throughout the region vary widely, but much of it ranges from in elevation.Mount Meru, the second highest mountain in Tanzania after Mount Kilimanjaro, peaks at . Arusha Region has the highest number of craters and extinct volcanoes in Tanzania. Other prominent peaks and mountains include the Monduli Mountains, Mount Loolmalasin, Mount Lolkisale, Mount Longido, Gelai Volcano, and the Olduvai Gorge.