Every offshore oil exploration and energy generation project requires a firm sub-structure to safely transfer the structural, operational, and environmental loads to the competent ground below the sea bed. The complexity and heterogeneity of soils and rock masses across different geographies necessitate a high-quality geotechnical investigation to arrive at the design philosophy and dimensions of the foundation structures. Deep foundation elements are either gravity based, driven, or drilled and grouted composite piles. Drilled and Grouted (D&G) piles are generally employed in places where the driven pile is expected to refuse before the target penetration depth. The axial pile capacity of D&G tubular piles is evaluated using similar methods as for driven piles. The end-bearing component of the D&G pile is not considered due to the inability to ensure that the pile bore base is sufficiently clean of cuttings and debris to enable full resistance to develop without excessive settlement of the pile. This paper presents a case study on the D&G composite pile, which contains a combination of driven sleeve pile and insert D&G pile. Target drilling depth was achieved initially, and the D&G pile’s P1 and P2 sleeve sections of the D&G pile were welded and lowered into the drilled hole. Further, to address seam orientation issues pile was lifted. During the subsequent lowering action, the pile fell 3.15 m short of target penetration and consequent limitations of pile capacity rating were a concern. Further, root cause and re-analysis were performed for as-installed pile penetration. Sensitivity analysis for various grout thickness values, qualitative assessments considering conservative site scenarios, and back analysis of driven sleeve pile capacity based on pile driving records were carried out to establish as-installed D&G composite pile capacity. Furthermore, the requisite safety factor for operational conditions was assessed to establish pile acceptance.