The increasing demand for sustainable construction has led to innovative approaches to utilizing industrial waste materials. This study investigates the use of waste foundry sand, pond ash, and cement in developing flowable fill, or Controlled Low Strength Material, for geotechnical and pavement applications. By incorporating waste foundry sand, a by-product of metal casting, and pond ash, a residue from coal-fired power plants, the method addresses waste disposal challenges while promoting sustainability. The objective is to create a self-compacting, low-strength material suitable for backfilling, pavement base layers, and other construction applications. Material characterization shows that waste foundry sand is a poorly graded sand with a specific gravity of 2.55, maximum dry density of 15.4 kN/m3, optimum moisture content of 23%, and permeability (k) of 1 × 10−5 cm/s. Pond ash is classified as silty sand, with a specific gravity of 2.80, maximum dry density of 14.85 kN/m3, optimum moisture content of 25%, and permeability of 1 × 10−6 cm/s. Leachate analysis of waste foundry sand confirms that the concentrations of heavy metals are within the permissible limits specified for inert waste. Flowable fill mix proportions having 2% and 3% cement content by dry mass of waste foundry sand and pond ash-to-cement ratios of 2.5, 5, and 7.5 were tested for fresh properties. Flow diameters ranging from 200 to 300 mm and bleeding values between 2 and 5.5% were observed, indicating adequate self-compaction and stability of the mixes.