Afghans in Iran (Persian: افغانستانی‌ها در ایران) are citizens of Afghanistan who are temporarily residing in Iran as refugees or asylum seekers. They form the largest percent of the Afghan diaspora. The first wave of Afghans crossed into Iran after the start of the Soviet–Afghan War in 1979.

According to Afghanistan's Ministry of Refugees and Repatriation and the United Nations High Commissioner for Refugees (UNHCR), there were approximately three million Afghan citizens in Iran as of January 2023, most of whom were born and raised in Iran during the last four decades. They are under the care and protection of the UNHCR, and are provided time-limited legal status by Iran's Bureau of Aliens and Foreign Immigrant Affairs, without a path to obtain permanent residency. There are also about 600,000 Afghan tourists, travelers, merchants, exchanged students, regular or irregular migrant workers, and others. According to Hassan Kazemi Qomi, half of Iran's foreign investors are Afghans.

There have been widespread reports of Iranian mistreatment of Afghan migrants and their human rights, and the community is very marginalized. In 2006, about 146,387 undocumented Afghans were deported. Many more continue to experience such events. In 2010, six Afghan prisoners were executed by hanging in the streets of Iran, which sparked angry demonstrations in Afghanistan. In August 2024 Iran ordered all undocumented Afghan citizens to return to their country before a one-year deadline. As of October 2025, around 4.5 million Afghans still remain in Iran.

As neighboring countries with cultural ties, there has been a long history of population movements between Iran and Afghanistan. Southern Afghanistan was contested between the Persian Safavid dynasty and the Moghuls of India until 1709 when Mir Wais Hotak, founder of the Hotaki dynasty, declared it independent. During the reign of Nader Shah, the brother of Ahmad Shah Durrani was made Governor of Mazandaran province. A few years after Nader Shah's death, Durrani and his Afghan army made Nader's grandson Shahrokh Afshar, ruler of the small remaining Afshar territory comprising the Khorasan and Kohistan provinces of Iran, their vassal for some years. The region remained a vassal territory of the Afghan Empire until Durrani's death. During the early 19th century, the Persian army invaded Herat several times but with British assistance the Afghans quickly expelled them. Communities made up of 2,000 and 5,000 households of ethnic Hazaras were formed in Torbat-e Jam and Bakharz in Iran. The 1857 Treaty of Paris ended hostilities of the Anglo-Persian War. The modern day Afghan–Iranian border gradually began to take shape in the second half of the 19th century.

Afghan migrant workers, pilgrims and merchants, who settled in Iran over the years, had by the early 20th century, become large enough to be officially classified as their own ethnic group, referred to variously as Khavari or Barbari. Young Hazara men have embraced migrant work in Iran and other Persian Gulf states to save money for marriage and become independent; such work has even come to be seen as a "rite of passage". Such migration intensified in the early 1970s due to famine, and by 1978, there were an estimated several hundred thousand Afghan migrant workers in Iran.

The Soviet–Afghan War, which erupted in 1979, was the beginning of a series of major waves of refugee flight from Afghanistan. Those who came to Iran often augmented the ranks of migrant workers already there. The new Islamic Republic took place around the same time as the influx of masses of Afghan migrants to other countries, fleeing the plagues of problems in their own country. Iran started recognising those Afghans listed as migrants workers or refugees as legals. They issued them "blue cards" to denote their status, entitling them to free primary and secondary education, as well as subsidised healthcare and food. However, the government maintained some restrictions on their employment, namely prohibiting them from owning their own businesses or working as street vendors.

Most of the early academic attention on these new immigrants was focused on Afghan refugees in Pakistan. Studies on Afghans in Iran came later due to the political situation during the Iran–Iraq War. By 1992, a report by the United Nations High Commissioner for Refugees (UNHCR) estimated that there were around 2.8 million Afghans in Iran. Just 10% were housed in refugee camps; most settled in or near urban areas. For their efforts in housing and educating these refugees and illegals, the Iranian government received little financial aid from the international community. With the fall of the Najibullah government of Afghanistan in 1992, Iran began efforts to encourage refugees to repatriate. During these years, there were many reports of cases of Afghans being harassed by Iranian law enforcement officers. Legal residents had their identity cards confiscated and exchanged with temporary residency permits of one-month validity, at the expiry of which they were expected to have left Iran and have repatriated.

Since 2002 millions of Afghan citizens living in Iran and Pakistan have returned to Afghanistan. In 2012, around 173,000 of them were forcefully returned. Over 103,086 more were deported in 2013. Many of the deportees complained of torture and other abuses by Iranian authorities. In October 2020 there were 780,000 registered citizens of Afghanistan residing in Iran. Most of these were born and raised in Iran during the last four decades. In 2015, Abdolreza Rahmani Fazli stated that 2.5 million Afghans resided in Iran, which includes the registered and illegals as well as those who were admitted to the country with Afghan passports and Iranian visas. Over 600,000 Afghans living in Iran have returned to Afghanistan in 2022. Afghanistan's Ministry of Refugees and Repatriation has acknowledged that approximately 3 million Afghan citizens still remain in Iran.