In Taiwan, electricity demand has increased steadily over the years, while the old buildings are not constructed with stringent energy-saving regulations, the inefficient and aging lighting systems with improper maintenance often lead to lighting quality decline and energy waste. In recent years, with the emergence of high-efficiency lighting technologies, the retrofitting of lighting systems has become one of the most widely adopted energy saving measures. This study focuses on nine cases of Green Building Renovation Projects from 2013 to 2015 in southern Taiwan, analyzes the payback period and the life cycle costing of the energy saving and economic benefits by lighting retrofit. The results shows that in addition to improving the indoor lighting quality such as illumination, uniformity and glare, through light source and fixtures efficiency improvement, reducing the number of lamps, zone control and utilization of renewable energy, the lighting retrofit strategies has reached an average of 36.3% reduction in lighting energy consumption and the average payback period is 5.76 years for construction costs. Also, taking into account the maintenance costs and the present value factors, the average life cycle cost after lighting retrofit is 22.6% lower than the un-retrofit scenario, while the life cycle cost after retrofit will be lower than the un-retrofit scenario in the seventh year, meaning the lighting retrofit can achieve economic benefit within the 20 years of lighting system durability. Moreover, the lighting retrofit methods are relatively easy, which is suitable for existing buildings and can be applied immediately.