Heterocyclic compounds are recognized to possess a high grade of structural diversity and a broad spectrum of therapeutic properties. About two-thirds of the New Chemical Entities approved by the FDA against cancer entail heterocyclic rings and are the foundation stone of medicinal chemistry. Pyrimidine being a major heterocyclic compound and a crucial base component of the genetic material, has emerged as the key structural component against cancer, the deadliest disease worldwide. Though many drugs are marketed against cancer, researchers are still investigating the more promising moieties against various malignancies due to the severity of this disease. In this review, an attempt has been made to assemble the reported literature of the previous five years on various synthetic procedures and the anti-cancer potential of various classes of fused pyrimidine analogs, which would help the researchers in designing new potent derivatives. Besides this, the review intends to focus on the comprehensive discussion on biological targets, modes of action, and structure-activity relationships of each class of fused pyrimidines as potential anticancer agents.