Hydroponic crop cultivation systems are a key component of controlled environment agriculture (CEA), where precision nutrient management is essential for sustainable plant growth and optimal yields, particularly in recycled hydroponic systems. Traditional methods, such as visual diagnosis of nutrient deficiencies or toxicities, are often delayed and prone to misinterpretation due to overlapping symptoms. Moreover, similar symptoms caused by different nutrient deficiencies can lead to confusion and result in incorrect nutrient replenishment. Although electrical conductivity (EC) based nutrient management techniques can be applied for online nutrient management, they only provide information about the overall ion concentration, limiting individual ion identification and quantification. Moreover, fluctuations in pH levels affect the availability of several ions by inducing precipitation or dissolution reactions. Ion-specific sensing techniques can play a vital role in overcoming these limitations. This article aims to provide a comprehensive overview of various sensing/monitoring technologies for precision nutrient management from an application perspective. Nowadays, ion-selective electrodes (ISEs) are widely investigated in hydroponic applications due to their sensing capabilities, real-time functionality, robustness, low cost, and calibration needs. This study discusses the factors affecting the sensing performance of different sensors, especially ion-based sensing, and commercial tools available in hydroponic operations. The review identifies future research priorities to enhance nutrient monitoring and decision-support systems for precision hydroponic nutrient management. This work aims to serve as a valuable resource for researchers and practitioners in advancing hydroponic sensing technologies.