The significance of multithreading in programming lies in its ability to optimize resource use and enhance application performance. By executing multiple threads concurrently within a single process, multithreading allows tasks to run in parallel, leading to improved responsiveness and better CPU utilization. It is particularly beneficial for applications that demand high levels of concurrency, such as web servers or user interfaces. However, effective multithreading requires careful management to avoid issues like race conditions and ensure accurate data handling.