This study evaluated the effects of suspended solids derived from Palm Oil Mill Effluent (POME) on soil chemical properties, nutrient uptake, physiological responses, and early performance of immature oil palm. The experiment was conducted from June 2024 to March 2025 at PT Bumitama Gunajaya Agro (BGA), Central Kalimantan, Indonesia, using a randomized complete block design with two treatments: solid POME application (25 kg plant⁻¹) and a non-solid control, both receiving identical inorganic fertilization. Agronomic, biochemical, plant nutrient, and soil chemical parameters were assessed six months after application. Solid POME markedly improved soil organic carbon, cation exchange capacity, available and total nutrients, and exchangeable base cations, resulting in clear treatment separation in PCA, with the first component explaining over 80% of total variance. These improvements enhanced nutrient accumulation in frond and leaflet tissues, particularly N, P, K, and Ca, indicating improved nutrient uptake and internal allocation. Vegetative growth responses were limited at this early stage; however, solid POME significantly increased the number of female inflorescences, suggesting stimulation of early reproductive differentiation. Physiologically, solid POME reduced oxidative stress, as evidenced by lower SOD, POD, proline, and MDA levels, while increasing catalase and nitrate reductase activity, reflecting improved metabolic stability. Correlation analysis confirmed strong linkages between improved soil fertility, enhanced nutrient status, and reduced physiological stress. Overall, suspended solid POME functioned as an effective soil conditioner, enhancing soil fertility, nutrient use efficiency, and physiological stability of oil palm grown on marginal soils.