The need for sustainable and environmentally friendly informal economic activities (IEA) has drawn keen interest of professionals and policymakers in the built environment. This study therefore examines the physical planning implications of IEA in Araromi Spare Part Market, Ibadan, Nigeria. The study aimed to provide insights on the nature of activities and actors involved in IEA within the study area, determine the existing condition of market infrastructure and traders’ satisfaction level, and examine the physical planning implications of IEA arising from market operations. Multistage sampling was used in selecting 185 traders for questionnaire administration. Data were analysed using frequency distribution, percentages and multi-criteria analysis. The study showed that basic infrastructure necessary for the market operations such as fire-fighting service, refuse disposal bay, and health facilities were unavailable. The Infrastructure Satisfaction Index ( \(\overline{ISI}\) ) value was 2.11; indicating that traders were dissatisfied with the market infrastructure. Findings also revealed that most traders were male (65.4%), married (63.2%), and had a mean age of 46 years. The mean monthly income of the traders was ₦160,550.48. The market operates daily with full-time traders providing local and regional services in the sales of tyres, iron, cars, and lorry parts. The identified planning implications were perceived as severe with a Perceived Implication Index ( \(\overline{PII}\) ) value of 3.92. Topmost of the challenges are bad access roads (3.92), poor market layout (3.72), noise pollution (3.50) and stall congestion (3.33). This research provides useful insights for the development control activities needed in balancing IEA with sustainable images of cities. The study recommends a bottom-top approach for the management of urban markets as well as effective monitoring and enforcement of planning standards.