The function of a compiler in computer programming is to translate source code written in a high-level programming language into machine code, which can be executed by a computer's CPU. Compilers optimize the code during this process, improving efficiency and performance of the resulting executable. They also check for syntax errors, helping developers identify issues before runtime. This transformation facilitates the development of applications across various platforms, as compilers enable programmers to write in languages like C, C++, or Java, which are more user-friendly than machine-level code.