Tree-shaking in React removes unused code from production bundles by analyzing ES module imports and eliminating dead code paths. With over 12 years of React experience since 2014 and as the creator of CoreUI, I’ve optimized bundle sizes through proper tree-shaking. Modern bundlers like Webpack and Vite automatically tree-shake ES modules, but proper import patterns are crucial for effectiveness. This approach significantly reduces JavaScript payload by including only code actually used in the application.