Schmallenberg virus (SBV; genus Orthobunyavirus) emerged in mainland Europe in 2011 and causes febrile disease in adult ruminants following transmission by Culicoides midges. Infection in utero causes abortion and congenital malformations in neonatal sheep, cattle, and goats. The virus was first detected in the United Kingdom in 2012, followed by a second outbreak in 2016–2017. A third emergence of SBV subsequently occurred during 2023–2024, with extensive spread throughout England, Wales, and Scotland. Here, we describe the dissemination of SBV during this most recent outbreak, from its initial detection in south-west England to widespread circulation across Great Britain within three months. Sequencing of SBV isolates from the 2023–2024 UK outbreak resulted in the assembly of one complete genome and near-complete M-segment sequences from a further four isolates, enabling comparisons between outbreaks. Phylogenetic analysis of the M segment, incorporating viruses from all three UK outbreaks together with representative mainland European SBV sequences, demonstrated distinct clustering of viruses from the two most recent UK outbreaks. These findings indicate repeated introductions of genetically distinct SBV lineages into the UK rather than re-emergence through cryptic endemic transmission of a single lineage. Our findings demonstrate the cyclical reintroduction of SBV into the UK at approximately 4–6-year intervals, followed by rapid dissemination throughout the national livestock population. Together, this work demonstrates the continuing threat posed by repeated SBV incursions into the UK livestock population and emphasises the importance of sustained genomic surveillance and reconsideration of vaccination strategies to mitigate future outbreaks.