The aim of this paper is to shed light on the way the European Parliament's diplomacy affects EU power, particularly during times of crisis. The analysis is focused on the Cox–Kwasniewski mission that the Parliament sent to Ukraine in 2012–13. Based on interviews and existing literature, we discuss the genesis and the development of the mission and then evaluate its impact. We argue that the mission with time became a key diplomatic instrument and enabled EU power projection by giving momentum to the promotion of the EU's approach towards Ukraine, which was already wavering due to the deadlock over the Association Agreement between Kyiv and Brussels and then due to President Yanukovych's refusal to sign the agreement.