Developing DNA‐encoded libraries of privileged scaffolds, such as pyrrolopyrimidines, is of great interest in drug discovery and chemical biology as a powerful tool to rapidly and inexpensively discover potent drug candidates. However, it is often challenging to construct such DNA‐encoded libraries because many reaction conditions are not compatible with DNA. Here, we describe the development of a convenient solid‐phase synthetic strategy that overcomes the current limitations and allows the efficient synthesis of a DNA‐encoded combinatorial library of structurally diverse tetra‐substituted pyrrolo[2,3‐d]pyrimidines.