Previous studies indicated that the persisting poor productivity issues in construction projects are a result of several factors which may not have been adequately researched. This research aimed to add to existing knowledge by investigating the key determinants of construction project productivity performance and improvement measures from the Australian construction industry perspectives. Based on descriptive survey research method, feedback was sought from consultants and contractors in relation to the research aim. Results of principal component analysis and partial least square structural equation modeling of the empirical data showed that productivity performance (Pp) outcome on a construction project could be underpinned by the head contracting firm’s strengths in three key areas. These comprise capacity & capability (CC), project management (PM), and contractual and financial management (CFM) competencies. 29 indicators were used for measuring the three constructs. In diminishing order of influence, the following were found to have the most significant influence on productivity outcomes: Digital technology-enhanced workflow and real-time project tracking, experienced workforce, relational contracting, robust quality assurance planning, and effective project supervision and coordination. Partial least square structural equation modeling results showed that the CC competency could be directly linked to Pp, but optimized and significant performance outcome draws strongly upon the mediating influence of the PM competency, interacting with and being supported by the CFM competency. The CC-Pp direct cause-and-effect relationship was unaffected by firm size. The findings could offer valuable insights to project stakeholders on the key underpinnings of effective project and financial management of construction projects. Practical implementation of the findings in real world could enhance productivity and success in project delivery. The methodology is recommended for investigating similar problems in Australia and elsewhere.