[48][49] Kata'ib Hezbollah has received extensive training, funding, logistic support, weapons, and intelligence from the IRGC's overseas military-intelligence service Quds Force.

[51] The group was founded by Jamal Jafaar al-Ibrahim, known as Abu Mahdi al-Muhandis, an Iraqi-Iranian dual national designated as a terrorist by US in 2009.

Arthur R. McGill was killed in Baghdad, when a makeshift bomb planted by Kata'ib Hezbollah exploded while he was on mounted patrol in a Humvee.

[60] On 17 October 2006, four U.S. servicemembers were killed when the Buffalo MRAP they were riding in was struck by an improvised-explosive device west of Baghdad at about 6:50 a.m.[61] The attack was captured on video and posted online by KH.

On 27 February 2007, three American soldiers were killed and another was wounded by a roadside bomb planted by KH militants in the Iraqi capital.

[67][68] On 20 November 2007, Alfred G. Paredez Jr. was killed when Kata'ib Hezbollah cell members detonated an IED in al-Baladiyat neighborhood of Baghdad.

[69] On 4 June 2008, KH conducted a rocket attack that was meant to target Coalition forces but instead killed 18 civilians in Baghdad.

[74] On 12 February 2010, a firefight with suspected members of the group occurred 265 km (165 mi) southeast of Baghdad in a village near the Iranian border, the U.S. military said.

[76] On 6 June 2011, KH militants fired rockets at Forward Operating Base Loyalty in eastern Baghdad killing six U.S.

[80] In July 2011, an Iraqi intelligence official estimated the group's size at 1,000 fighters and said the militants were paid between $300 and $500 per month.

[83][84] Wathiq al-Batat, a former KH leader, announced the creation of a new Shia militia, the Mukhtar Army, on 4 February 2013, saying its aim is to defend Shiites and help the government combat terrorism.

[91] The airstrikes targeted three KH locations in Iraq and two in Syria, and included weapons depots and command posts, according to Reuters and a US military statement.

[101] On 25 June 2020, Iraqi security forces raided KH base in Dora, southern Baghdad and detained at least 14 militia members.

[107] On 17 November 2023, United States expanded the scope of sanctions on KH by blacklisting six high-ranking officials affiliated with the militia following attacks on U.S. forces in Iraq and Syria.

[115] On 30 January 2024, KH announced the suspension of all its military operations against US forces in the region after the Tower 22 drone attack which killed 3 US soldiers and injured 47 others.

[117] Later that year, on 20 September, Kata'ib Hezbollah announced that Abu Haidar al-Khafaji, a senior commander in the group, was killed by an airstrike about 5 kilometres (3.1 mi) away from Sayyidah Zaynab near Damascus, Syria, and blamed Israel for the attack.

[118] In 2013, KH and other Iraqi Shia militias acknowledged sending fighters to Syria to fight alongside forces loyal to President Bashar al-Assad, against the Sunni rebels seeking to overthrow him in the Syrian Civil War.

[44] On 9 January 2024, the KH spokesperson Jafar al-Husseini warned that the Islamic Resistance in Iraq would help Hezbollah fight Israel if war erupted between the two sides.

[122] In April 2024, Abu Ali al-Askari, security chief of Kata'ib Hezbollah based in Iraq, said the organisation was prepared to arm "Islamic Resistance" in Jordan and is ready to provide "12,000 fighters with light and medium weapons, anti-armor launchers, tactical missiles, millions of rounds of ammunition, and tons of explosives" to "defend the Palestinians and avenge the honour of Muslims."