Abstract. The article explores the strengthening of Ukrainian-British diplomatic relations over the course of the ruscist aggression against Ukraine. The author argues that diplomacy has become an efficient asset that can play a crucial role in assuring Ukraine’s victory in the struggle against the aggressor. The study focuses on the consistent and effective support for Ukraine extended by the United Kingdom and the latter’s unyielding opposition to russia’s aggressive expansionist policy. The article highlights the rapid development of Ukrainian-British relations, referring to the signing of agreements on political cooperation, free trade, and strategic partnership between the two countries in October 2020. The United Kingdom seeks to form alliances with like-minded countries to support Ukraine. Specifically, the author mentions the initiative to establish a trilateral alliance between Ukraine, the UK, and Poland to enhance security and foster economic cooperation. Additionally, he emphasises the importance of intensive diplomatic contacts and visits by Boris Johnson to Kyiv, which bolstered the coordination in providing support and assistance to Ukraine. Moreover, the paper references the notable Ukraine Recovery Conference in London, highlighting the pivotal role of the international community in supporting and rebuilding Ukraine. Overall, the article underscores that the United Kingdom remains one of Ukraine’s closest friends that promotes the expansion and enhancement of support from other Western partners. While the author acknowledges the presence of diverse political stances on the issue within British society, he concludes that Ukraine will undoubtedly continue to play a prominent role in the United Kingdom’s foreign policy, cementing the latter’s role in the fight for European and transatlantic security. Keywords: Ukraine, Great Britain, diplomacy, Ukrainian-British diplomatic relations, ruscist aggression.