Pyrimidine derivatives have attracted much attention in medicinal chemistry because of their diversified biological properties and potential therapeutic applications. The Suzuki‐Miyaura, Sonogashira, and Buchwald‐Hartwig coupling reactions provide flexible methods for synthesizing structurally diverse pyrimidine derivatives. These reactions can modify the pyrimidine structure to incorporate different functional groups and substitution patterns, improving the pharmacological activities and maximizing the drug‐like properties. Using other coupling partners, such as aryl and heteroaryl moieties, has produced novel pyrimidine‐based scaffolds with enhanced bioactivity profiles. This comprehensive review examines the biological activities of pyrimidine derivatives, concentrating on how their diversification via coupling reactions utilizing synthetic techniques has affected their pharmacological properties. Investigating various biological effects and exploring novel artificial techniques present great opportunities for creating next‐generation medicines with improved efficacy and selectivity.