Spectroscopy approaches showed promising results for the precise quantitative and qualitative assessment of plants and plant-based products which are characterized by complex microstructures and chemical compositions. Presently, the new generation of cutting-edge spectroscopic techniques such as visible-infrared (VIS-NIR), Raman spectroscopy, nuclear magnetic resonance (NMR), spectral imaging, etc. are emerging as rapid, non-destructive, largely reproducible, easy to use and cost-effective which aligns with the practical requirements of plant research. However, their performance can be influenced by factors including spectral interference, matrix complexity, instrumental variability, and calibration robustness—challenges that may affect sensitivity and reproducibility. These spectroscopic techniques have been employed in various aspects of plant sciences, including compositional analysis, nutritional profiling, and the detection of contaminants, adulterants, environmental monitoring, and stress markers. Moreover, they contribute to genetic and metabolic profiling, supporting advancements in plant breeding and biotechnology. This paper provides an objective and comprehensive overview of the current applications of spectroscopic analyses based on the state-of-the-art literature written in English and published in peer-reviewed journals from 2000 to 2024, aimed to elucidate the varied applications of spectroscopy in plant sciences, highlighting its indispensable role in addressing upcoming challenges in the plant and plant-based food industry and promoting sustainable practices. Spectroscopy, in its ever-evolving form, will play a main role in the future of smart agriculture, sustaining plant and plant-based foods amidst climate change.