Climate change has emerged as a major determinant of vector-borne disease dynamics worldwide. Rising temperatures, altered precipitation patterns, and increasing frequency of extreme weather events have significantly influenced the geographic distribution and seasonal activity of Aedes aegypti, the primary vector of dengue fever. This systematic review synthesizes global evidence on the relationship between climate variability and the spatial expansion of A. aegypti, and its impact on dengue epidemiology. A structured literature search was conducted in PubMed, Scopus, and Web of Science for studies published between 2010 and 2026, including epidemiological analyses, climate-model projections, entomological surveys, and outbreak reports examining associations between climatic factors and vector distribution or disease incidence. Findings demonstrate a poleward and altitudinal expansion of A. aegypti, with the vector now reported at altitudes of 1000–1500 m and in over 50 countries previously considered non-endemic. Increased mean temperatures and extended warm seasons were associated with higher vector survival, shorter viral incubation periods, and prolonged transmission seasons. Globally, dengue infections affect approximately 390 million people annually, of which ~96 million are symptomatic, and recent data show a 30–50% increase in reported cases in Asia and Latin America over the past decade. Climate variability has contributed to dengue emergence in temperate zones and intensification of outbreaks in endemic regions. Predictive models suggest that by 2050, the population at risk could increase by ~1.2 billion worldwide. These results highlight that climate-driven expansion of Aedes aegypti is reshaping dengue epidemiology, increasing both geographic spread and transmission intensity. Strengthened climate-informed surveillance, integrated vector management, and adaptive public health strategies are urgently needed to mitigate the growing global burden of dengue.