On 31 January 2020, the United Kingdom officially withdrew from the European Union (EU). Brexit will reduce the EU global outreach in specific areas in which the role of the UK was essential. The Gulf is one of them. Brexit is also happening as the era of the Anglosaxon hegemony in the Gulf is coming to an end. What here is defined as the active Gulf has replaced the passive Gulf, a process that has been in the making for a while. This means that a geopolitical vacuum that needs to be filled – either by regional or external actors – is emerging. As no external actor can play in the Gulf the role played by the UK and the US in the past; mounting security dilemmas are affecting more and more the views and perceptions of regional actors. This article aims at analysing these dynamics in the light of Brexit and how these two dynamics can impact the EU-GCC historically dysfunctional liaison. In order to do so, the paper will use the lens and language of geopolitics. The post-Brexit EU, thus, will have to interact with the Active Gulf. The EU will fail to provide an alternative to the US as a potential external security provider, and the absence of the UK from the EU ranks will also preclude the EU from having a crucial driver to deepen these relations further.