Typically, ionospheric delay can be modeled using two primary approaches: Global Ionospheric Models (GIMs) and Regional Ionospheric Models (RIMs). GIMs provide a broad representation of ionospheric conditions worldwide, using data collected from a global network of GNSS receivers to estimate global Total Electron Content (TEC) maps at regular intervals. However, they may lack precision in localized areas due to their lower spatial and temporal resolution. RIMs, on the other hand, are localized models that represent ionospheric conditions over a specific geographic area with higher resolution and accuracy than GIMs. Developed using data from dense networks of ground-based GNSS receivers within a region, RIMs can account for localized ionospheric variations more effectively than global models. This research estimates a Regional Ionospheric Model (RIM), based on spherical harmonic expansions, over the United Arab Emirates (UAE) by utilizing data from a dense network of GNSS receivers. Given the UAE’s location in a low-latitude zone, the ionosphere exhibits significant variations due to solar activity, geomagnetic influences, and seasonal effects, which can impact GNSS-based applications such as navigation, geodesy, and communication systems. Improvement in position accuracy using RIM is also analyzed and compared with GIMs. Our results showed that using RIM model can improve the positioning accuracy by about 43% for horizontal components and 25% for 3D component during summer season compared with 27% and 14% during winter season.