Creating a mobile-first strategy in web development is significant due to the increasing reliance on mobile devices for internet access. This approach prioritizes the design and functionality of websites for mobile users, ensuring that they have an optimal browsing experience. By focusing on mobile compatibility, developers can enhance user engagement and improve SEO performance, as search engines favor mobile-friendly sites. A mobile-first strategy also streamlines the development process and helps in addressing the responsive design challenges and screen size variations that modern web users encounter.