Current trends in the global energy market focus on gradually increasing the share of renewable energy sources in the overall energy mix. In recent years, there has been growing interest within the scientific community in assessing the suitability of cities for implementing solar energy solutions. This work discusses various research directions on the solar potential of urban areas, with a particular focus on the role of Geographic Information System (GIS) tools in support of spatial analyses. The main aim of the study was to update the current state of the research based on the analysis of previous works. An attempt was made to assess the role of GIS in research on the solar potential of cities in the context of the overall investigation process. A total of 201 case studies published between 1999 and 2024 (year to date) were analysed, among which articles from 2019–24 were examined in detail. The analysis revealed a wide variation in the approaches regarding the spatial scale of studies and the sources of key data, such as shading and solar radiation. It was shown that one of the key challenges in current analyses is the lack of universality of the methodologies used, leading to divergent, and sometimes challenging to compare final results. In the research aspect, a global urban solar potential was estimated for cities with more than 1 million inhabitants, which amounted to 33.7 PW h annually.