In the present work, Ageratum houstonianum leaf acetone extract was tested for the larvicidal and growth inhibitory activity against the third instar larvae of the Dengue vector, Aedes aegypti. The extract showed larvicidal activity with LC50 and LC90 values of 204.79 and 277.57 mg/L, respectively. The larval mortality was increased during subsequent days of treatment. The extract adversely affected larval development, causing a significant reduction in both the formation of fourth instar larvae and pupae. Also, the extract increased the larval duration of Ae. aegypti third instar larvae indicating growth inhibitory activities of the extract. The results showed dose-dependent effects of the A. houstonianum leaf acetone extract; treatment at higher concentrations inhibited the growth and reduced the viability. This resulted in a decrease in the larval growth index. GC-MS analysis revealed the presence of precocene I and precocene II along with many other components which affect the survival and growth of the insects adversely. This explores the potential of A. houstonianum in the management of Ae. aegypti.