The real estate market is vital for economic growth, with the residential rental sector meeting critical urban housing needs. In Nigeria, rapid urbanization, poverty, and inadequate formal housing have fueled the expansion of informal settlements. This study analyzes trends in residential rental values in Ibadan Metropolis’s informal settlements from 2014 to 2024. Using a descriptive and inferential design, data were collected from 360 residents and 34 estate surveyors across five Local Government Areas (LGAs) with high informal housing prevalence. A structured questionnaire (Cronbach Alpha = 0.83) ensured reliable data for Time Series Analysis and ANOVA. Findings show significant rental increases across all LGAs. In Ibadan North East, a room self-contained rose by 130.8% from ₦65,000 to ₦150,000, while bungalow rents grew by 200% from ₦250,000 to ₦750,000. Ibadan North showed moderate growth: room tenements increased from ₦25,000 to ₦55,000, and three-bedroom flats from ₦100,000 to ₦150,000. In Ibadan South East, South West, and North West, two-bedroom flats doubled from ₦100,000 to ₦200,000, and three-bedroom flats rose from ₦100,000 to ₦250,000. ANOVA confirmed these changes are statistically significant (p < 0.05). Poverty (mean scores: 4.34–5.45) and rapid urbanization (4.26–5.42) were key drivers, alongside weak housing policies, informal land markets, and poor infrastructure. The study concludes that without targeted policy interventions and improved infrastructure, informal settlements will continue to expand alongside rising rental values and worsening affordability challenges for low-income urban residents. It recommends that urban policymakers prioritize inclusive housing policies, strengthen infrastructure provision, regulate informal land transactions, and implement community-focused socio-economic programs to improve residents’ livelihoods and housing conditions sustainably.