The past two decades have been marked by the growth of a rich and robust scholarship on transnational Islamist militancy (Hansen 2013; Hegghammer 2010a, 2010b, 2013, 2020; Kepel 2000, 2017; Lia 2008; Moghaddam 2017; Robinson 2020; Roy 2017). These accounts often highlight the sheer global character of recent acts of Islamist militancy. They tackle the growth of militant ideologies which do not recognize national borders such as Salafism (Moghadam 2009; Wagemakers 2009, 2012; Maher 2016), the spread of transnational Islamist networks (Abou Zahab and Roy 2004; Pall 2016; Jaffrelot 2017), or again the global scope and reach of groups such as Al-Qaeda and ISIS, which not only carry out attacks throughout the world but, in addition to their local base, also recruit many foreign fighters (Byman 2015, 2019; Hegghammer 2010; Joffé 2016; Mallet 2013). Yet, in spite of all this progresses, the scholarship suffers from an important gap which may bias the analysis of the transnational dynamics of armed Islamism: it overwhelmingly relies on Sunni examples and overlooks Shia Islamist transnationalism. This gap is a crucial one to address. Lebanon’s Shia Hezbollah was arguably the first Islamist armed group to pioneer attacks on transnational targets, as demonstrated by its involvement in the 1994 bombing of Jewish community centre in Argentina and the 1995 Khobar Towers attack aiming at US military personnel stationed in Saudi Arabia. Iraq’s Daawa Party, for its part, may have been the first truly transnational Islamist armed group as it operated throughout the Gulf in the 1980s and drew Shia members from Iraq but also from Lebanon, Bahrain, Saudi Arabia, Kuwait, and Afghanistan (Jabbar 2003, Louer 2008). In other words, militant Shia Islamism has also been largely transnational in its reach and scope, but its analysis has rarely been factored in broader accounts about global jihad. This raises important questions which this paper seeks to address. To what extent and how are transnational Shia militant Islamist groups similar/different from Sunni counterparts? What, if any, are the peculiar factors which drive transnational Shia Islamist militancy? Is the phenomenon one that cuts across sub-ideological categories of Shia Islamism, or one which is underpinned by particular political ideologies – such as for example, Khomeinist Islamism? How precisely does the role of external sponsorship matter when accounting for Shia transnational activism? And how truly transnational is the phenomenon?