Graphene plasmonics offers a promising platform for strong light-matter interactions due to its superior confinement and tunability compared to noble-metal plasmons. The authors report strong light-matter interactions assisted by graphene plasmons, including high decay rates of quantum emitters near a carbon sheet, large vacuum Rabi splitting, and Purcell factors, as well as extinction cross sections exceeding the geometrical area in graphene ribbons and nanometer-sized disks. These properties enable the development of quantum plasmonics and single-molecule, single-plasmon devices. The unique combination of extreme field confinement, tunability, and low losses in graphene makes it an ideal material for advanced optoelectronic applications, such as cavity quantum electrodynamics and novel photonic and optoelectronic devices. The study also explores the engineering of plasmonic nanostructures, including nanoribbons and nanodisks, to enhance coupling efficiency and achieve resonant extinction cross-sections that exceed their geometrical areas. Additionally, the strong coupling between single emitters and single plasmons in graphene nanodisks allows for the observation of vacuum Rabi splitting, indicating the possibility of reversible and coherent re-absorption of emitted plasmons. Overall, the work highlights the potential of graphene plasmonics in advancing quantum optics and nanoscale light-matter interactions.Graphene plasmonics offers a promising platform for strong light-matter interactions due to its superior confinement and tunability compared to noble-metal plasmons. The authors report strong light-matter interactions assisted by graphene plasmons, including high decay rates of quantum emitters near a carbon sheet, large vacuum Rabi splitting, and Purcell factors, as well as extinction cross sections exceeding the geometrical area in graphene ribbons and nanometer-sized disks. These properties enable the development of quantum plasmonics and single-molecule, single-plasmon devices. The unique combination of extreme field confinement, tunability, and low losses in graphene makes it an ideal material for advanced optoelectronic applications, such as cavity quantum electrodynamics and novel photonic and optoelectronic devices. The study also explores the engineering of plasmonic nanostructures, including nanoribbons and nanodisks, to enhance coupling efficiency and achieve resonant extinction cross-sections that exceed their geometrical areas. Additionally, the strong coupling between single emitters and single plasmons in graphene nanodisks allows for the observation of vacuum Rabi splitting, indicating the possibility of reversible and coherent re-absorption of emitted plasmons. Overall, the work highlights the potential of graphene plasmonics in advancing quantum optics and nanoscale light-matter interactions.