Transportation is considered as the fundamental factor for mobility as every individual is highly dependent on transportation so that they have access to jobs, goods and other services. Increasing demand for motorization is causing congestion issues in quickly growing urban communities. Islamabad, capital city of Pakistan, along with its neighboring city Rawalpindi initiated a metro bus service to ease the traffic congestion problem and to reduce the atmospheric pollution. This study aimed to analyze the mode shift behavior of commuters from public transport, own transport and taxi after the implementation of metro bus service. The study used logistic regression because the dependent variable is binary in nature. Secondly, the study was aimed to find out the carbon emissions reduced after the launch of metro bus service in the region. The results of the study indicated that commuters are more willing to shift towards metro bus for job and education purpose. Female travelers are more willing to use metro bus service as compared to males. Income shows no effect on mode shift behavior. The study also found that metro bus has the potential to reduce travel cost of around PKR 1000 per month and travel time of around 23 minutes per month. Lastly it found that metro bus service has the potential to clean the environment by reducing carbon emissions, as it replaced approximately 700 public vehicles from the route, resulting in the reduction of around 8000 metric tons of carbon emissions from the region Supervisor:- Dr. Muhammad Irfan