Since the discovery of metallic conductivity in iodine-doped polyacetylene that eventually led to the 2000 Nobel Prize in Chemistry, conjugated polymers have attracted enormous attention in both academia and industry ascribed to the outstanding optoelectronic properties, flexibility, and solution processability and hold great potential for the development of next-generation soft electronics. Traditionally, the synthesis of conjugated polymers predominantly involves carbon–carbon single bond formation between functionalized aromatic building blocks, which is often seen displaying nonconjugation or home-coupling defects that adversely affect the polymer properties and the performance of fabricated devices. Alternatively, alkene and alkyne metathesis reactions offer a privileged pathway toward conjugated polymers with well-defined microstructures, defect-free backbones, customized terminal functional groups, and high molecular weight. From a historical account of metathesis polymerization, this chapter provides a comprehensive review on ring-opening metathesis polymerization, acyclic diyne metathesis polymerization, ring-opening alkyne metathesis polymerization, and acyclic diyne metathesis polymerization in the synthesis of functional conjugated polymers that possess intriguing optical and electronic properties. This section was closed with a short summary and outlook about the potential direction of alkene and alkyne metathesis polymerizations.