Due to the increasing concern about climate change and environmental sustainability, the investigation of energy consumption represents a very intriguing and undeniable subject. This study was directed to investigate energy footprints, greenhouse gas (GHG) emissions and life cycle assessment (LCA) of the main vegetable crops cultivated under open field conditions in southern Egypt. Potato production required the maximum energy amount (112.3 GJ/ha) compared to 76 GJ and 96 GJ for onion and tomato, respectively. Based on energy indices, potato gave (energy ratio > 1; energy productivity > 1; energy profitability > 1; net energy > 0), while onion and tomato production shared the same indicators (energy ratio < 1; energy productivity > 1; energy profitability < 0; net energy < 0). However, GHG emissions generated for producing one ton of potato tubers registered the least amount by 76.0 kg CO2 eq. The same GHG amount was produced by 834 kg of onion bulbs and 940.6 kg of tomato fruits. The emission rates were more a consequence of diesel, followed by inorganic fertilizer and manure. In addition to carbon emissions, every production process causes several other environmental problems, thus a comprehensive analysis of environmental impact categories is required. The openLCA program performed LCA and ten impact categories were considered to transform the inventory data into several indicators. Producing one ton of potato tubers has the least footprint on the environment and the ecosystem, such as global warming (GW)—238.8 kg CO2 eq. t−1; human toxicity (HT)—288.3 kg 1,4-DB eq. t−1; fresh water aquatic ecotoxicity (FAEF)—160.44 kg 1,4-DB eq. t−1; marine aquatic ecotoxicity (MAET)—365,636 kg 1,4-DB eq. t−1; and terrestrial ecotoxicity (TE)—1.18 kg 1,4-DB eq. t−1. The analyses indicated that machinery and diesel fuel had the highest impact on all the studied categories.