Wheat dwarf disease (WDD) is an economically important cereal disease caused by Mastrevirus hordei (wheat dwarf virus, WDV), transmitted in a persistent manner by the leafhopper Psammotettix alienus. Climate-driven expansion of this vector has increased WDV prevalence across Europe, including Ukraine. This study aimed to survey cereal crops in various regions of Ukraine to assess WDV prevalence and analyze the genetic diversity and phylogenetic relationships of the detected isolates based on partial coat protein gene sequences. Surveys conducted in June 2025 revealed that severe outbreaks of WDD in western and northern Ukraine were caused by WDV, as confirmed by DAS-ELISA and PCR in 40 samples (out of 142 tested) from 21 districts across seven regions. Phylogenetic analysis of partial coat protein gene sequences showed that WDV isolates detected in Ukraine in 2024–2025 exhibited low nucleotide diversity and formed a well-supported monophyletic cluster within clade E. This cluster was distinct from earlier Ukrainian isolates (2008–2020), although those isolates also belonged to clade E. The only exception was WDV-Uk-Odessa (2009), which grouped within clade A together with Central and Eastern European isolates. These results indicate that clade E is now firmly established in Ukraine, with recent isolates representing a new evolutionary lineage spreading across different host species. The widespread distribution of P. alienus in Ukraine emphasizes the risk of further WDV expansion and potential outbreaks across all cereal-growing regions.