Increasing demand for food with minimal traces of chemicals is challenging viticulture to move away from chemical weeding. In France, there is increasing trend towards mechanical weeding, but it is repetitive, labour intensive, and costly to farmers. Autonomous robotic systems may help tackle the labour challenge while also providing opportunities to improve input use efficiency and minimize CO2 emission. This study provides a cost benefit analysis of robotic mechanical weeding relative to conventional practices of chemical weeding and mechanical weeding using tractor based on a case study in France. The results show that the robotic system generates a little less net present value but considerably reduces labour and fuel use compared to conventional practice.