Evaluating land suitability is crucial for guiding sustainable agricultural land management in tropical agroecosystems. This research assessed the suitability of land for cultivating paddy rice (Oryza sativa L.) in South Sulawesi, Indonesia, by combining Geographic Information System (GIS) analysis with laboratory-based soil characterization. The FAO maximum-limitation framework was employed within GIS to evaluate land suitability, utilizing 12 characteristics obtained from field surveys and laboratory analyses. GIS land mapping units (LMUs) were categorized into S2na (moderately suitable) or S3na (marginally suitable) classes, with nutrient availability (na) being the limiting factor throughout the study area. All physical land parameters, such as drainage, texture, effective rooting depth (>50 cm), soil pH (5.78–6.82), slope gradient (<8%), erosion risk, and flood risk, achieved S1 (highly suitable) ratings across all mapping units. Meanwhile, cation exchange capacity (CEC = 18.82–26.00 cmol(+)/kg) reached S1 in most mapping units, although reduced nutrient-retention capacity (S2–S3) further limited three units. The main limiting factors were critically low available phosphorus (P2O5 = 9.82–14.92 mg/100 g) and low-to-very-low total nitrogen (N-total = 0.08–0.24%), exacerbated by insufficient soil organic carbon (C-Organic = 0.76–2.44%) in several units. The IAERI identified varying levels of agro-environmental risk among LMUs, highlighting nutrient limitations as the dominant constraint to paddy production. The integration of GIS, soil fertility diagnostics, and IAERI provides a spatial decision-support framework for sustainable paddy land management.