A sustainable urban form needs to accommodate a mix of varied compatible land uses with ample open-space ratio (OSR) through transformation. This study, thus, aims to examine the sustainability of land-use transformation patterns from the perspective of sub-Saharan African cities. It also analyses consequences of formal planning interventions and organic developments on OSR, both in the inner city and the periphery. Hence, land-use mix and OSR are compared over time at both plot and neighbourhood level, which is both scholarly and practical. The research study includes six cases from three morphological periods. The results indicate that the intensity of mixed-land use declined over time at the plot, while the figure increased at neighbourhood level. Besides, moving from the historic core to the periphery reduces the intensity of mixed-land use at the neighbourhood level. Across years, the intensity of mixed-land use showed a decreasing trend reflecting a reduction in the sustainable urban form. To avert this, cities need to integrate practices and principles of both organic development and formal planning endeavours. In addition, the existence of ample OSR helps to improve a balanced mix of uses at both the plot and neighbourhood level.