The purpose of a compiler in computer programming is to translate high-level programming languages into machine code that a computer's processor can execute. Compilers take source code written by developers and convert it into an executable form, allowing the program to run on a specific platform. This process involves several stages, including lexical analysis, syntax analysis, and code generation. Compilers play a crucial role in optimizing code for performance, enabling developers to write in more human-readable syntax while still achieving efficient execution.