The Tigray war, also referred to in some academic and policy sources as the Northern Ethiopia Conflict, was an armed conflict that lasted from 3 November 2020 to 3 November 2022. It was a civil war that was primarily fought in the Tigray Region of Ethiopia between forces allied with the Ethiopian federal government and Eritrea on one side, and the Tigray People's Liberation Front (TPLF) on the other. It is generally considered to be the deadliest war fought in the 21st century.

After years of increased tensions and hostilities between the TPLF and the governments of Ethiopia and Eritrea, fighting began when TPLF forces attacked the Northern Command headquarters of the Ethiopian National Defense Force (ENDF), alongside a number of other bases in Tigray. The ENDF counterattacked from the south – while Eritrean Defence Forces (EDF) began launching attacks from the north – which Prime Minister Abiy Ahmed described as a "law enforcement operation". Federal allied forces captured Mekelle, the capital of the Tigray Region, on 28 November, after which Abiy declared the operation "over." However, the TPLF stated soon afterwards that it would continue fighting until the "invaders" were out, and on 28 June 2021, the Tigray Defense Forces (TDF) retook Mekelle; by July the same year, they had also advanced into the Amhara and Afar regions. In early November 2021, the TDF, together with the Oromo Liberation Army (OLA), took control of several towns on the highway south from Tigray Region towards Addis Ababa, and the TPLF stated that it considered "marching on [the capital]." Together with seven smaller rebel groups, the TPLF and OLA declared a coalition aiming to "dismantle Abiy's government by force or by negotiations, and then form a transitional authority."

After a successful government counter-offensive in response, and then a series of negotiations with the TPLF, Ethiopia declared an indefinite humanitarian truce on 24 March 2022, in order to allow the delivery of humanitarian aid into Tigray. However, fighting dramatically re-escalated in late August 2022, after peace talks broke down. Rapid mobilization of troops soon followed, with Ethiopia, Eritrea and Tigray reportedly organizing hundreds of thousands of troops against each other by October the same year. After a number of peace and mediation proposals in the intervening years, Ethiopia and the Tigrayan rebel forces agreed to a cessation of hostilities on 2 November, which went into effect the day after; Eritrea was not a party to the agreement, however, and they largely continued to occupy parts of Tigray as of 2023.

All sides, particularly the ENDF, EDF, Amhara forces and TDF, committed war crimes during the conflict. Mass extrajudicial killings of civilians took place throughout, including in Axum, Bora, Chenna, Kobo, the Hitsats refugee camp, Humera, Mai Kadra, the Mahbere Dego, and Zalambessa. Additionally, the ENDF and EDF were accused of genocide. Between 162,000 and 378,000 people were killed, and war rape became a "daily" occurrence, with girls as young as 8 and women as old as 72 being raped, often in front of their families. A survey found that, over the course of the conflict, around 1 in 10 women in Tigray were subjected to sexual violence, 8 in 100 were subjected to rape, and 4 in 100 were subjected to gang rape. Nails, screws, plastic rubbish and other foreign bodies were forced into reproductive organs of women, in what was seen as part of a wider effort to destroy fertility of women in Tigray.

A major humanitarian crisis developed as a result of the war, which led to a widespread famine. It also inflicted immense economic damage on the region, with the cost of rebuilding alone estimated to be roughly $20 billion.

Following the end of the Ethiopian Civil War in 1991, Ethiopia became a dominant-party state under the rule of the Ethiopian People's Revolutionary Democratic Front (EPRDF), a coalition of four ethnically based parties. The founding and most influential member was the Tigray People's Liberation Front (TPLF), led by Meles Zenawi, who was the prime minister of Ethiopia until his death in 2012. He was succeeded by Deputy Prime Minister Hailemariam Desalegn, the chairman of the Southern Ethiopian People's Democratic Movement (SEPDM), a coalition member. On 15 February 2018, Hailemariam announced his resignation as both prime minister and chairman of the EPRDF, owing to a growing discontent within the public, fueled by a reaction to 27 years of repressive governance.

On 28 March 2018, in a closed-door election to chair the EPRDF, executive committee members elected the Oromo Peoples' Democratic Organisation (OPDO) chairman Abiy Ahmed. On 2 April 2018, Ethiopian parliament elected Abiy as prime minister. One of Abiy's first actions after his election was to initiate a warming of relations with Eritrea, a long-time rival of the TPLF, to end a 20-year long border conflict. While this decision was considered a cause of celebration at the time, many within the Tigray Region were heavily critical of this, seeing it as a betrayal of those who died in the 1998–2000 war. The TPLF condemned the peace initiatives, saying they were hastily made, had "fundamental flaws", and also claimed it was decided on without consulting long-time TPLF members.

On 1 December 2019, Abiy merged the ethnic and region-based parties of the EPRDF (which had governed Ethiopia for 28 years) and several opposition parties into his new Prosperity Party. The TPLF, which had long dominated Ethiopian politics, refused to join this new party. After losing the election and being ousted from the federal government, TPLF officials relocated to the Tigray Region, continuing to administer control there while frequently clashing with the federal government. In one instance, the Tigray regional government was reported to have defied the federal government and refused to allow Ethiopian Federal Police to arrest Getachew Assefa, the former chief of the National Intelligence and Security Service (NISS) of Ethiopia and executive member of the TPLF.