Using industrial waste materials in the treatment of problematic soils is an environmentally friendly and cost-effective technique. It helps in decreasing disposal issues induced by various industrial wastes. Also, it is crucial to understand the behaviour of these waste products before use. This paper presents experimental research in the treatment of expansive soil by the utilization of iron furnace slag. Laboratory program was performed to examine the effect of iron furnace slag on enhancing the engineering properties of expansive soil. Several tests included liquid limits, plastic limits, free swell percentage, swelling pressure, and unconfined compressive strength were conducted on untreated and treated soils. The efficiency of adding 0, 2, 4, and 6 percentages of iron slag to the soil was investigated. The results of the natural and iron slag stabilized soils showed that iron slag has a notable effect on strength parameters and considerable improvement in plasticity and swelling properties. The addition of iron slag to the soil increased the unconfined compressive strength while reduced the swelling potential of soil. It is concluded that the utilization of iron slag to improve the properties of expansive soil is successful and useful