Sulfur and its functional groups are major players in an area of exciting research taking place in modern polymer and materials science, both in academia and industry. In fact, manifold sulfur-based reactions that are both exceptionally versatile as well as tremendously useful have been implemented, and further utilized for the design and preparation of polymeric materials that lead to a plethora of applications ranging from medicine to optics and nanotechnology to separation science. Hence, within this review, an overview of strategies and developments used over the last 5 years to reinforce the importance of the sulfur functional group in modern polymer and materials science is presented. In particular, many important references in the primary literature of sulfur chemistry are referred to, including thiol-ene, thiol-yne, thiol-Michael addition, disulfide cross-linking, and thiol-disulfide exchange, among others, by explaining and illustrating the important principles. Last but not least, the grand aim to underpin the importance of sulfur in modern polymer and materials science is achieved by presenting selected examples in diverse fields and postulating the respective potential for real-world applications.