Nyeri is a town situated in the Central Highlands of Kenya. It is the county headquarters of Nyeri County and was the central administrative headquarters of the country's former Central Province. The town is situated about 150 km north of Kenya's capital Nairobi, in the country's densely populated and fertile Central Highlands. The town lies between the eastern base of the Nyandarua (Aberdare) Range, which forms part of the eastern end of the Great Rift Valley, and the western slopes of Mount Kenya.

The town's population, according to the 2019 Kenya Population and Housing Census, was estimated at 140,338 inhabitants. However, the number is rapidly growing. There is, however, a significant population of primarily Government and corporate workers who ordinarily reside in Nyeri but who, during the census, choose to be counted in their areas of origin or the areas where their families are residents. The town has a relatively low cost of living in comparison to Nairobi and other major urban centres in Kenya. Located in Kenya's fertile highlands, food and water are plentiful and relatively affordable.

Nyeri hosts the tomb of Robert Baden-Powell, the founder of the Scout movement. It is also the home town of the late Nobel laureate Wangari Maathai. The town is also the home of the Dedan Kimathi University of Technology (DeKUT), founded by the local community in the early 1970s as an institute of technology, and converted into a fully fledged university in 2012.

Towards the end of 1902, as the British were establishing their colonial presence, Richard Meinertzhagen marched a strong military column meeting spirited resistance from the native Kikuyu warriors led by Wangombe Wa Ihura. The Kikuyu were eventually defeated. After Meinertzhagen's victory, a decision was reached to site a British post close to a little hill on the slopes of Mt. Kenya. The Kikuyu called the hill Kia-Nyiri while their Maasai neighbours called the hill Na-aier. The post took its name from the little hill. On 18 December 1902, Nyeri was founded.

Shortly after the establishment of the post, a trickle of European settlers and missionaries and Indian merchants began to migrate into Nyeri and the surrounding areas. The city soon burgeoned into a trading centre for white settler farmers who produced cattle, wheat and coffee. The city became particularly associated with the Happy Valley set in the first half of the twentieth century. The Nyeri Golf Club, The White Rhino Hotel, Outspan Hotel, and the Aberdare Country Club at the nearby Mweiga township are relics of those colonial days.

The majority of Nyeri residents are members of Kenya's largest ethnic group, the Kikuyu, with residents generally being known as "Nyeri Kikuyu". The Kikuyu language is widely spoken, along with Kenya's National language Swahili as well as Kenya's official language English.

Following the national pattern of Kenya being a predominantly Christian country, Christianity is the main religion. The main Christian denominations are Catholic-that hosts the Cathedral and the Archbishop's official residence-, Presbyterian, Anglican, Pentecostals and indigenous denominations, in that order. The older residents, who tend to attend the mainstream churches, are invariably more religious than the younger ones. Muslims, traditional African believers and Hindus, in declining order, make up a small minority.

About 5 km from the city centre is the Mathari Mission settlement, a complex of several Catholic buildings and institutions, established by Italian missionaries at the beginning of the 20th century. The mission is composed of convents for nuns, schools, a teacher training college and other vocational colleges. It also hosts the Consolata Hospital and School of Nursing, which is staffed largely by nuns of the Consolata order. Nyeri is also the place where Blessed Stephanie Nyaatha was laid to rest.