While autonomous machines are considered as a new opportunity to augment safety, reliability, productivity, and efficiency, the actual environmental and economic sustainability performances of many autonomous systems remain yet to be quantified. The present research aims to fill part of this gap by evaluating the life cycle impact and cost of autonomous solutions in the agricultural industry. Comparative life cycle assessment (LCA) and life cycle costing (LCC) are carried out on a real-world case study putting in parallel a robotic electric lawn mower (autonomous solution) and conventional-gasoline-and electricity-powered-pushing mowers (human-operated counterparts). Results are interpreted in terms of global warming potential and total cost of ownership. While the autonomous system already appears to be a promising sustainable alternative, discussions and quantitative insights are also provided on the conditions that would lead to further environmental savings and economic profit for this autonomous solution.