Soil properties are critical in building and road construction, which often causes problems, particularly for clay-type soil. The poor condition of clay soil is indicated by its high plasticity, low shear strength, high volume changes, and high shrinking properties. In the current work, marble waste powder (MWP) was used as an additive to stabilize the soil. The investigation aims to study the effect of the weight percentage of MWP addition and to cure time on the soil stabilization properties. Soil samples were taken from Jalan Masjid Priyayi, Kasemen, and Serang. Variations of marble powder waste were 0, 7, 17, and 27%-wt with a curing time of 0, 7, 14, and 28 days. The soil tests were performed for sieve analysis, soil density, moisture content, Atterberg (liquid limit), soil compaction, and unconfined compressive strength (UCS) tests. The study results found that the soil was categorized as OH-type organic clay with high plasticity according to the Unified Soil Classification System (USCS) classification. The plasticity index value decreased with the increase in the content of MWP. The effect of curing time is highly influential in increasing the UCS value. The longer the curing time, the higher the UCS value. The highest UCS value obtained after adding 7% MWP with 28 days of curing was 3.427 kg/cm 2 from only 0.749 kg/cm 2 in the clay soil before mixing with MWP. The addition of low-cost MWP effectively improves clay soil stabilization.