In an urbanization process, infrastructure elements such as tunnels and deep excavations are widely used to service the development of cities. Owing to the lengthy geological processes of geomaterials and the limited availability of site-specific test data, soil and rock properties exhibiting spatial variability are frequently encountered in geological and geotechnical engineering. This paper presents a comprehensive review of the application of spatial variability in tunneling and deep excavation over the past 20 years. It is found that the spatial variability is generally modeled as a random field (RF) in finite element software, based on random field theory (RFT). This model has been widely used in the design, stability evaluation, and probabilistic analysis of tunnels and excavations. Previous works have proven that the performance of tunnels and deep excavations can be better captured by considering the spatial variability, as compared with conventional deterministic analysis methods. Nonetheless, current research still faces many factual scientific problems. Therefore, this paper also identifies some research gaps, as well as recommendations for further investigations.