In May 2014, Serbia was hit by a catastrophic flooding event. The Municipality of Obrenovac suffered severe consequences due to a number of reasons, mainly the poor conditions of flood protection infrastructure and outdated land use management. These problems have been triggered and/or affected by the post-socialist transition of Serbia, initiated during the 1990s. The ongoing period of socio-economic turbulences, also detected in other countries with a similar development background, caused a shift in both the planning paradigm and the economy (from a planned/centralized model to a market-oriented model), creating numerous problems related to the synchronization of legislation, governance, implementation and management. Considering the specificities of local context, as well as its similarities to other post-socialist countries, the main aims of the article are to establish a relationship between planning, legislation and flood resilience, identify its (un)sustainable elements and provide an insight into the dynamic of their causal links whose effectiveness could be improved in given conditions. The main findings indicate an absence of a sustainable policy which would guarantee efficient implementation (regarding both planning documents and laws). Simultaneously, there were other challenges—from the lack of risk assessment to outdated regulations and general unpreparedness which led to severe damage of urban systems and local economy, while many lives were lost. Consequently, the article provides guidelines for new planning documents, suggesting measures that would increase the resilience of flood protection (applicable in both local and regional context), as well as the overall sustainability of the analyzed area and its ecosystem.