Abstract Petroliam Nasional Berhad (PETRONAS) engineered, fabricated, and installed offshore wellhead light weight structure known as Platform A, at 70m water depth with bridge link to the existing platform, offshore Peninsular Malaysia. During offshore installation of the substructure, the top section of main leg was deflected laterally by approximately 2.65 m from the target position. Post inspection survey by remotely operated vehicle (ROV) during offshore installation time has confirmed there was a deflection on the substructure however the survey method has been known to have lower accuracy while substructure structural integrity assessment required precise input data for valid results. Further analysis to verify the substructure structural integrity is done by performing In-Place and Fatigue analysis considering residual stresses based on actual as-installed condition of the substructure. As part of the assessment, 3D subsea photogrammetry survey technology has been deployed to verify the substructure verticality and deflection using accurate underwater survey measurement technique. The emerging 3D subsea photogrammetry survey technology was used to achieve high accuracy and stringent subsea relative survey measurement, replacing the conventional method using diver and less accurate underwater positioning system by Ultra-short baseline (USBL) which is not comprehensively covered the entire substructure components. The method avoided the complex survey and positioning systems set-up that would consume longer installation and calibration time and pose greater Health, Safety, Security and Environment (HSSE) risks and exposures during operation. The 3D subsea photogrammetry survey was executed by utilizing 3D imaging video camera attached on the work class ROV which integrated with the survey-grade subsea gyrocompass, motion sensor and interfaced with navigation system to achieve accurate and seamless underwater photogrammetry survey. 3D model of the substructure was generated for accurate 3D model analysis and study for structural integrity verification. The reliable survey data has allowed structural integrity reassessment to be conducted to finalize the analysis report through modeling refinement, content presentation to reflect latest 3D survey report and would not jeopardize the current fitness-of-purpose structural integrity of Platform A. The results demonstrated that the 3D subsea photogrammetry survey achieved centimeter level accuracy in relative surveying measurement, while gaining operational cost benefits by diverless operation, reducing operational time where the survey was conducted simultaneously with General Visual Inspection (GVI) by the ROV and eliminating uncertainty on data accuracy and coverage. It also reduced HSSE risks exposure by minimizing ROV diving and tasking operations and improved situational awareness by real-time video and continuous high definition (HD) photo taking to generate photo realistic model of point cloud. This paper discusses the implementation of the 3D subsea photogrammetry survey technology, highlighting its technical capabilities, challenges encountered during offshore operations, perceived value creation, and the valuable technological experiences gained. These insights can be leveraged for broader subsea inspection, installation and monitoring applications.