To survive in challenging environments, plants must rapidly activate immune responses while maintaining developmental plasticity and reproductive success. This requires continuous negotiation of limited energy and metabolic resources between growth, development, and defense. Ubiquitin-mediated proteolysis has emerged as a versatile regulatory mechanism that may integrate immune responses with plant developmental programs. In this review, we summarize accumulating evidence that ubiquitination shapes immune responses at multiple regulatory levels. Many of these immune-regulatory mechanisms depend on ubiquitin-dependent pathways that also govern developmental processes and cell cycle regulation. This overlap points to shared molecular nodes that integrate defense with growth. This functional overlap provides a mechanistic basis for growth–defense trade-offs and highlights how plants optimize fitness under stress conditions. Together, these findings position ubiquitin-mediated proteolysis as a unifying regulatory framework through which plants integrate immune responses with developmental programs and cell cycle control. This coordination helps maintain resilience and productivity in a fluctuating environment.