Landslides are the most common natural disaster that impact millions, costing tens of thousands of lives and billions of dollars in damage each year. There are many cases of landslides in India, especially in hilly regions such as North East India, which are caused by heavy rainfall and earthquakes. For geotechnical engineers, one of the most challenging aspects is to ensure that the slope will remain safe for a long period of time regardless of heavy rain and earthquake strikes. North East India has experienced heavy rainfall in recent years accompanied by several minor earthquakes, which has caused a repetition of landslide occurrences in hilly areas, especially during monsoon season. In this study, the stability and deformation of a vulnerable slope located in Itanagar, the capital complex of Arunachal Pradesh, is investigated using finite element-based pseudo-static analysis. The study utilized the rainfall intensity data collected from the NASA power database and for earthquake probabilistic peak ground acceleration values from the Indian Geological Survey Report for the study area. Stability and deformation of the slope are analyzed by a numerical simulation model using PLAXIS 2D software. A number of parametric studies are being conducted using soil parameters, slope parameters, earthquake parameters, and rainfall parameters. The factor of safety as well as the maximum displacement of the slope both in horizontal and vertical direction have also been reported in extreme scenario to gain insight into the slope’s response based on rainfall intensities, peak ground acceleration (PGA), and site characteristics. It has been observed that seismic acceleration has a greater impact on slope stability as compared to the rainfall infiltration. The study emphasizes the importance of analyzing seismic data along with rainwater seepage in slope stability particularly in landslide-prone areas for disaster prevention and safety evaluation.