This chapter outlines colorimetric sensor arrays and their significance in identifying and measuring analytes by observing changes in colorimetric reactions. Further, it explores the characteristics of different substrates commonly employed in these arrays, such as paper, glass, polymer, nanoporous material substrates, and nanoparticle-packed surfaces. Each substrate is thoroughly examined including manufacturing techniques, surface alterations, and vital features affecting the sensors effectiveness. The chapter investigates the basic principles behind substrate selection refinement to improve the performance and versatility of colorimetric sensor arrays across various sensing tasks. Additionally, it surveys the diverse applications of these arrays in environmental monitoring, biomedical diagnostics, food safety, industrial monitoring, and other explored domains. Furthermore, it delves into ongoing trends, and advancements in substrate design and creation, addressing obstacles and prospects in the field.