This study investigated using textile mill sludge as a partial replacement for fine aggregate in concrete. Textile mill sludge is a waste produced during effluent treatment at textile plants. The sludge was partially replaced at dosages of 10%, 20%, and 30% of the fine aggregate content in M35 grade concrete. Concrete cubes, cylinders, and prisms were cast and tested at 7, 14, and 28 days to determine the compressive, split tensile, and flexural strengths. The results showed that compressive strength decreased with increasing sludge content replacement, with up to 30% replacement achieving strengths over 30% of the control mix. This suggests textile mill sludge can partially replace fine aggregate in concrete