Reliable geotechnical investigation is crucial for designing safe and stable foundations in coastal and deltaic environments, where subsurface soils are often highly variable, compressible, and weak near the surface. This study provides a detailed geotechnical assessment of the subsurface conditions at a proposed three-storey building site in Gbarian Clan, Yenagoa, within the Niger Delta region of Nigeria. Two boreholes extending to 25 m were drilled, and both disturbed and undisturbed samples were obtained for laboratory analysis following BS 1377 and ASTM Procedures. The testing program included direct shear tests for granular soils and unconfined compressive strength (UCS) tests for cohesive soils. The results show that the upper 3–6 m consists mainly of soft to firm clay with undrained shear strengths (Su) ranging from 15–35 kPa. These clays display moderate to high compressibility and low bearing capacity, conditions that could lead to significant settlement under applied loads. Below approximately 9 m, the soil profile transitions to dense to very dense sands, characterized by high friction angles (φ = 40.7°–45.9°), indicating strong, competent bearing layers with minimal compressibility. UCS values for the clay samples range from 30.15–69.53 kPa, reflecting an increase in strength with depth due to the effects of overburden pressure. Bearing capacity evaluations based on Terzaghi’s equations show that shallow foundations founded within the dense sand layers would be structurally adequate, while the softer upper clay horizons may require ground improvement or the adoption of deep foundation systems. Overall, the findings are consistent with known Niger Delta geology and provide essential data for determining appropriate foundation solutions for the project site