The subject of completion of project is a universal concern that affects all parties to a construction project. Various studies show that construction industry accounts for an estimated 10% of the gross national product (GNP) of most developed economies, with reports indicating that the resources utilized in this industry add up to 50% of the world resources. It is thus in the interest of the project management as an emerging profession to address all the factors that affect completion of construction project. This is because contractors usually have limited ability to claim additional money which is limited to the circumstances where the project company has delayed the contractor or has ordered the variation of the works. Reports indicate that more than 50% of all public building construction projects started by the county government in the lasts two years have gone beyond the stipulated completion time. Although the government has been making efforts to address the issue by issuing directives and legislations aimed at improving the situation, indications are quite clear that case of delays, cost overruns and below quality deliveries are still rampant. This study, therefore, sought to establish the factors influencing completion of building construction projects in Kajiado County. The study adopted a pragmatic research paradigm for a mixed research method in a concurrent research design. The study targeted all the project management personnel in Kajiado County, with the sample size being calculated based on the formula by Yamane (1967) through both probability and non-probability sampling techniques. The sample size was 212 respondents comprising of chief officers, technical staff, contractors, and sub-county project managers. Structured questionnaires were administered to collect quantitative data from selected county and subcounty project managers as well as the National Construction Authority personnel. Regression models were used to analyse quantitative data. The study found that fund allocation, project management factors, as well as human resource factors had a positive correlation with the completion of building construction projects in Kajiado County. Project identification process on the other hand displayed negative correlation with the completion of building construction projects in Kajiado County. A study concluded that compliance regulations aid fund allocation, project identification, human resource, and project management in ensuring successful completion of building construction projects in Kajiado County. The study recommended that all project managers in Kajiado County comply with the construction standards and regulations in place before embarking on project construction, ensure project funds are set aside for the same, and procure all the required materials before start of the project.
