Consultants play a pivotal role in public construction procurement by providing technical, managerial and advisory services that shape project outcomes. Despite their importance, procurement inefficiencies persist in Nigeria, raising concerns about the effectiveness of consultancy services, particularly in Abuja where federal construction activities are concentrated. This study examines the extent to which consultants impact the procurement of public construction projects in Abuja, Nigeria. A mixed-methods research design adopting a convergent parallel approach was employed. Quantitative data were collected through structured questionnaires administered to 391 public construction stakeholders, while qualitative data were obtained through semi-structured interviews conducted 8 professionals. Descriptive statistics and non-parametric tests, including the Kruskal–Wallis test, were used to analyze quantitative data, complemented by thematic analysis of qualitative responses. The findings indicate that consultants exert the greatest influence during project implementation (Mean = 4.12), contract execution (Mean = 4.09) and stakeholder engagement (Mean = 4.04). Moderate influence was observed in risk management (Mean = 3.89), quality assurance (Mean = 3.87) and environmental and social impact assessment (Mean = 3.83), while minimal influence was recorded in early-stage procurement activities such as advertisement (Mean = 2.49), approval (Mean = 2.86) and contract award (Mean = 2.93). Hypothesis testing revealed no statistically significant variation in stakeholder perceptions of consultant impact across procurement stages (H = 6.637, p = .156), indicating broad consensus among stakeholder groups. Qualitative findings further demonstrate that consultants contribute substantially to cost control, time management, quality assurance and regulatory compliance, although their technical recommendations are sometimes constrained by administrative and political factors. The study concludes that consultants significantly influence public construction procurement outcomes in Abuja, particularly during implementation and contract administration phases. It recommends enhanced early-stage consultant involvement and the development of a standardized performance evaluation framework aligned with Nigeria’s public procurement system to strengthen accountability, value for money and project delivery outcomes.