Post-translational modifications (PTMs) are at the heart of many cellular signaling events. Apart from a single regulatory PTM, there are also PTMs that function in orchestrated manners. Such PTM crosstalk usually serves as a fine-tuning mechanism to adjust cellular responses to the slightest changes in the environment. While PTM crosstalk has been studied in depth in various species; in plants, this field is just emerging. In this review, we discuss recent studies on crosstalk between three of the most common protein PTMs in plant cells, being phosphorylation, ubiquitination, and sumoylation, and we highlight the diverse underlying mechanisms as well as signaling outputs of such crosstalk.