The Islamic Courts Union (Somali: Midowga Maxkamadaha Islaamiga) was a legal and political organization formed to address the lawlessness that had gripped Somalia since the fall of the Siad Barre regime in 1991 during the Somali Civil War.

During the early years of the Somali Civil War in Mogadishu, a new phenomenon emerged — the establishment of Sharia courts to impose law and order on various volatile neighborhoods of the city. These independent courts often found their existence being threatened by warlords, which necessitated cooperation between them that would eventually lead to their unification into the entity known as the Islamic Courts Union (ICU) in 2000. Comprising many different courts, the union was a diffuse organization with rivaling leaders sending conflicting messages about the group's goals. Some members had national political ambitions, while others wanted to focus on resolving local disputes and bringing people closer to Islam.

The ICU garnered widespread support among Somalis, who regarded Islam as one of the few remaining trustworthy institutions in the aftermath of the state's collapse. By originating from the grassroots level, asserting their governance under the mantle of religious impartiality and fighting the widely despised warlords controlling much of the city, the ICU rapidly gained the confidence of a populace exhausted by warfare. Given the country's pervasive wartime inter-clan tensions, the ruling of Islamic neutrality presented an alluring option to many Somali citizens.

In the summer of 2006, the ICU decisively defeated a Somali warlord alliance funded by the American Central Intelligence Agency and became the first entity to consolidate control over all of Mogadishu since the collapse of the state in 1991. The period that followed is commonly heralded as the most stable and productive period Somalia had seen up to that point since the outbreak of the civil war. Residents of Mogadishu were finally able to move around the city without fear of attack, the international airport and seaport were opened for the first time in over a decade, a massive rubbish clean up campaign was started and there was a significant reduction of arms on the streets. Six months into their reign, the Islamic Courts Union would be toppled during the final days of 2006 by an Ethiopian-led military intervention, supported by the United States. The organization would completely dissolve early in 2007 due to the invasion and internal disagreements. The 2006–2009 War in Somalia that followed would consequently bring internationally recognized Transitional Federal Government (TFG) to power.

Following the foreign intervention by Ethiopian forces in late 2006, most of the moderates governing the ICU would seek refuge abroad. Consequently, a radical militia of the Islamic Courts, the now-infamous Al-Shabaab stayed behind and invoked jihad against the American backed Ethiopian invasion, greatly empowering themselves as a resistance movement. High-ranking members of the Islamic Courts would later found the Alliance for the Re-liberation of Somalia in late 2007, which would later merge with the TFG. Former chairman of the Islamic Courts Union, Sharif Sheikh Ahmed, became president of Somalia in 2009, replacing successfully the Transitional Government with the Federal Government of Somalia. In 2012, the country adopted a new constitution that declared Somalia an Islamic state with Sharia as its primary source of law.