Click chemistry, also known as “link chemistry,” is an important molecular connection method that can achieve simple and efficient connections between specific small molecular groups at the molecular level. Click chemistry offers several advantages, including high efficiency, good selectivity, mild conditions, and few side reactions. These features make it a valuable tool for in-depth analysis of various protein posttranslational modifications (PTMs) caused by changes in cell metabolism during viral infection. This chapter considers the palmitoylation, carbonylation, and alkylation of STING and presents detailed information and experimental procedures for measuring PTMs using click chemistry.