Abstract With the increasing rate of urbanisation, the growing population and the increasing rate of consumption, the management of solid waste in the Federal Capital Territory (FCT) of Abuja is becoming an uphill task. Although there are policies and some private sector involvement in waste collection, the system is fragmented, disposal focused and lacks spatial balance. This study develops a context-specific Integrated Solid Waste Management System (ISWMS) for Abuja using a concurrent triangulation mixed-methods design. Quantitative data were obtained from 689 valid survey responses, including 494 households and 195 business, institutional, civil society and waste-sector respondents. Qualitative data were drawn from 23 key stakeholder interviews and focus group discussions with 24 informal waste sector actors comprising waste pickers, scrap dealers and recyclers. Descriptive statistics, regression analysis, chi-square tests, thematic coding and triangulation matrices were used to diagnose system performance and translate the evidence into a phased ISWMS model. Findings show that only 42.3% of households reported door-to-door collection, 28.1% experienced irregular collection, 14.4% used open dumping and 5.1% burned waste on site. Source segregation was low at 26.3%, while 66.4% of households were unaware of municipal waste regulations. Institutional fragmentation among AEPB, FMENV, NESREA, Area Councils and private contractors was confirmed by 69.6% of key informant’s interviews. At present, Abuja generates approximately 1.33 million tonnes of solid waste annually. This value is expected to rise to 1.84 million tonnes by 2035. The proposed Integrated Solid Waste Management System (ISWMS) is designed to capture waste management governance reform, phased investments in infrastructure, integration of the informal waste sector as cooperatives, sustainable financing of the system, and the introduction of performance monitoring. This article argues that the waste management challenges in Abuja are best understood as a systems governance challenge, and as such, a comprehensive and integrated reform approach is necessary to address the challenge, rather than piecemeal technical solutions. Keywords: integrated solid waste management; ISWMS; Abuja; municipal solid waste; circular economy; informal waste sector; waste governance; Nigeria