Productivity is the dominating aspect in construction as it encourages cost savings and effective utilization of resources. Poor labour productivity is one of the major causes of cost and time overrun in construction projects and as such requires attention. Previous studies have identified factors affecting labour productivity within building projects, however, there is need to understand these factors as it relates to their impact on cost and time. In view of this, the paper aimed at assessing the impact of factors affecting labour productivity on cost and time, with a view to minimizing their effects on construction projects. The study elicits knowledge gained by project managers actively engaged in construction projects within Abuja been the Federal Capital Territory and employed the use of a survey. A well-structured questionnaire was designed to collect data with respect to degree of impact of labour productivity factors on construction project cost, and time using a five-point Likert scale and distributed to 45 project managers using purposive sampling. Responses from the administered questionnaires were collated, interpreted, and analysed using descriptive statistics, and results presented in tables. The findings showed that material shortage at project site with a mean value of 3.68 had significant impact on construction project cost. Furthermore, lack of tools and equipment in the market, and workforce absenteeism with mean values of 3.65 and 3.62 respectively had significant impacts on construction project time. The study concludes that material shortage, lack of tools and equipment in the market, and workforce absenteeism are labour productivity factors that had significant impact on construction project cost and time. Thus, Construction managers should enforce the use of material supply schedule, and adopt appropriate financial incentives for employee’s that could curtail the problem of absenteeism.