Infrared spectroscopy monitors the interaction of chemical molecules with infrared light and the resulting vibrations. It offers speed, convenience, reliability, and accuracy to the analyst, and reduces cost, time, and labor in the industry. Its adoption for food and dairy analysis is relatively new, but the number of applications is increasing at a tremendous pace. Greater awareness is driving the demand for better instrumentation, miniaturization, and portability to enable on-site analysis for immediate results. In dairy analysis, the applications of infrared spectroscopy encompass two main areas: (1) quantification of concentrations and quality parameters and (2) testing of purity, identity, and adulteration. Numerous researchers are working on further extending the applications of this technique to industrial use, as well as dairy research. The main research focus is on using infrared spectroscopy to better understand changes in dairy products, ingredients, and microbial population during processing with the overall objective of optimizing processes for better and uniform product quality and safety. With several applications still unexplored and numerous ideas still in the development phase, infrared spectroscopy offers exciting research opportunities. This article introduces the theory of infrared spectroscopy and provides an overview of current applications in dairy analysis with relevant examples and illustrations.