Ultrafast plasmonics represents a cutting-edge frontier in light-matter interactions, providing a unique platform to study electronic interactions and collective motions across femtosecond to picosecond timescales. In the infrared regime, where energy aligns with the rearrangements of low-energy electrons, molecular vibrations, and thermal fluctuations, ultrafast plasmonics can be a powerful tool for revealing ultrafast electronic phase transitions, controlling molecular reactions, and driving subwavelength thermal processes. Here, the evolution of ultrafast infrared plasmonics, discussing the recent progress in their manipulation, detection, and applications is reviewed. The future opportunities, including their potential to probe electronic correlations, investigate intrinsic ultrafast plasmonic interactions, and enable advanced applications in quantum information are highlighted, which may be promoted by multi-physical field integrated ultrafast techniques.