Milk is one of the most valuable dairy products in the human diet, and its quality assessment is crucial in terms of safety, nutritional value, and public health. In recent decades, spectroscopic techniques have gained prominence due to their rapidity, accuracy, minimal sample preparation, and non-destructive nature. This review provides an overview of the most important spectroscopic methods, including optical spectroscopy, Raman spectroscopy, and infrared (IR) spectroscopy, for the qualitative and quantitative analysis of key milk components such as fat, protein, lactose, and other constituents. The role of nanotechnology in enhancing the sensitivity and efficiency of these methods is also discussed—particularly the application of nanostructures as enhancing substrates in Surface-Enhanced Raman Spectroscopy (SERS) and the development of nanosensors in IR spectroscopy, enabling the detection of contaminants and adulterants at trace levels. In the final section, advanced techniques such as Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR) spectroscopy are reviewed, along with a critical evaluation of their advantages and limitations. This study highlights how integrating spectroscopic methods with nanotechnology opens new avenues for rapid and precise milk quality monitoring.