Rapid urbanization is a global phenomenon driven by population growth and rural to urban migration. While urban expansion contributes to economic development, its also exerts significant pressure on natural resources, leading to environment degradation. This research examines the environmental implications of rapid urbanization in Islamabad, drawing on existing literature and is grounded in primary data collected through qualitative interviews with key government urban planners, environmental experts, academicians and civil society representatives from Pakistan. Based on the analysis of the data, this study argues that unregulated urban growth in Islamabad has disrupted the ecological balance, lost substantial green cover, experienced a sharp decline in groundwater levels and witnessed deteriorating air quality due to increased carbon emissions. Despite Pakistans commitment sustainable development, governance challenges, weak policy enforcement and political interference have exacerbated these environmental concerns. The unchecked urban sprawl threatens Islamabads ecological balance, public health and long term sustainability of Islamabad. The study recommends urgent sustainable urban planning, green infrastructure initiatives and public-private partnerships to mitigate the adverse effects of urbanization and promote environmental sustainability in Islamabad.