The construction industry is tasked with the obligation of delivering construction projects within a budgeted sum according to an estimated contract sum. Professionals in the construction industry aim to satisfy the ever-growing requirements of the client by employing various project management strategies out of which is delegation in regards to roles, skills, competencies, and so on. In order to bring these management policies into a functional state, success factors in regards to delegation towards construction projects were taken into consideration so as to achieve successful project delivery and sustainable project in the long run. With this, the research aimed at assessing the key success factors for successful delegation in construction project management as it also centered on the connection between effective project delegation strategy in increasing the project success verisimilitude and the construction project complexity. The literature aspect of the research gave an in-depth view of already published articles, journals, publications as well as other relevant documents regarding bringing to understanding the success factors in achieving successful project management through the delegation process. It covers exclusive inferences from previous researchers as well as analysis to back it all up. The analytical method employed was quantitative in nature as construction professionals were sent electronic questionnaires to fill out in Lagos state Nigeria. The analysis obtained gave an inference where 57.8% of the respondents admitted to having participated in the use of delegation process while carrying out construction projects. Furthermore, sampling the respondents in respect to influencing factors of project success across the phases of the construction project; environment ranked the most effective influencing factor with a mean rank of 3.98, the standard deviation of 1.208, and the least factor being identified as an organization with a mean and standard deviation of 2.52 and 1.151. In discussing project factors affecting construction success, the complexity of the project ranked the highest with a mean and standard deviation of 3.80 and 1.095 respectively. Control mechanism and implementing safety programs led the project management actions affecting project success with mean ranks and standard deviations of 3.70, 0.918, 3.65, and 1.111 respectively. External environment factors affecting project success correlated with each other as factors highlighted gave a coefficient correlation lesser than 1. This proved the interrelationship among the factors stated. Conclusively, it was deduced that the management contracting (MC), design-build/finance/operate (DBFO), and construction manager as a constructor (CMR) is the highest-ranked critical success factors for different project delivery methods with mean ranks of 3.58, 3.57, 3.49 and standard deviation of 0.908, 0.995, and 0.800 respectively. These project deliveries are factors that aid for successful delegation in project management with every method having a mean rank greater than 3.00. It is concluded that the construction professionals in the Nigerian and the general construction industry should inculcate the act of delegating activities in construction from the onset of operation to completion of the project. The delegated functions will, in turn, spin the construction team to want to get better at whatever function, and from such, there is a transfer of knowledge and development is bound to occur under such a situation. The development of a firm depends on how well a task is been delegated, so it is recommended that the delegation process should be properly carried out and evenly distributed for better project delivery and success within a set contract duration. Keywords: Project delivery; success factors; project success; delegation in construction