Beef production has notable environmental implications on a global scale. Paraguayan beef cattle farming is characterized by being developed mostly in pastures or grasslands, but recently the practice of finishing confined to feedlots has thrived. In this context, the aim of this study was to understand the environmental performance of a semi-intensive beef farm which involved in its production system both a pasture and a feedlot stage. A Life Cycle Assessment was carried out with a “cradle-to-farm gate” perspective and 1 kg of Live Weight as the functional unit. Primary data referring to cropping and livestock systems’ inputs and outputs were collected on site and a wide range of impact categories were evaluated. Beef cattle farming proved to be responsible for intensive greenhouse gas emissions (22.0 ± 3.9 kg CO2 eq ⋅ kg LW−1), especially when it occurs predominantly on pasture. The breeding phase is the one that weighs most on global warming potential within the rearing cycle. Since most animals are present in the pasture stage, this contributed highly to the impact categories influenced by animal-related emissions. The feedlot stage, despite its limited duration with respect to the overall rearing cycle, weighs significantly in the categories related to non-methane volatile organic compounds emissions, toxicity, land occupation and fuel consumption, especially because of feed production (both on- and off-farm). Moreover, this stage takes on a greater environmental load when considering the impacts of land use changes related to the consumption of purchased feed, even though its short duration reduces the relative variation given by land use changes inclusion. Some possible mitigation solutions were identified in the discussion, but further study is required into the implications of this topic and the exploration of different scenarios.