<p>Agricultural production is increasingly impacted by global anthropogenic pressures, including population growth, rising protein demand, and the intensification of climate extremes, all of which contribute to elevated greenhouse gas (GHG) emissions. Carbon footprint (CF) assessment is a critical tool for quantifying the environmental impacts of agricultural systems, yet comprehensive evaluations remain limited for many crops and regions. This study employs a Life Cycle Assessment (LCA) approach to investigate the CF of major crops in Türkiye, focusing on regional variations and the relationship between CF and input use efficiency. Data were collected from field surveys (totalling 1.530) and institutional records for wheat, barley, maize, and rice, accounting for both direct and indirect GHG emissions from key agricultural inputs such as fertilizers, irrigation, and mechanization. The analysis reveals substantial regional disparities in CF, particularly for wheat and barley, largely driven by differences in input use, cultivation practices, and environmental conditions. Rice production, despite exhibiting the highest CF per unit area and product, has a limited overall contribution to national emissions due to its restricted cultivation area. Fertilizer use emerged as the primary driver of emissions for wheat and barley, while combined fertilizer and irrigation inputs were dominant for maize, and methane emissions alongside fertilizer application were key for rice. Significant correlations were identified between CF and water-nitrogen use efficiencies, indicating that improving these efficiencies could substantially reduce CF, particularly in yield-based assessments. The findings emphasise the importance of region- and crop-specific CF assessments to inform strategies for reducing emissions and advancing sustainable agricultural practices in Türkiye under changing climatic conditions.</p>