absorbers (SAs) are widely used to obtain ultrafast lasers. Mode-locking indicates a fixed phase between longitudinal modes in spectral domain, while Q-switching refers to the giant pulse formation due to the tunable Q factor of the laser cavity. Saturable absorption represents the optical modulation that absorption coefficient of SAs decreases with the increase of incident optical intensity, where SAs are often categorized into artificial and real SAs. [7][8][9] Artificial SAs mainly consist of nonlinear polarization evolution, [10,11] nonlinear optical loop mirrors, [12][13][14] and nonlinear amplification loop mirrors, [15,16] which fulfill the function of saturable absorption by means of nonlinear effects. By contrast, real SAs are characterized by the inherent nonlinear absorption property of the materials. Semiconductor saturable absorber mirror is a typical real SA and widely used in diverse lasers. However, several drawbacks such as complex fabrication and narrow operating bandwidth restrict its applications. [17][18][19][20][21] Under such circumstances, nanomaterials emerge as SAs of distinction where 2D nanomaterials have been widely investigated because of the unique optical properties induced by the energy band structures. [22][23][24][25][26][27][28] Graphene possesses zero bandgap and ultrafast carrier dynamics properties, contributing to a broad operating bandwidth and fast response time. [29][30][31][32][33][34][35][36] Nevertheless, the modulation depth of ≈2.3% per layer limits Nanomaterials with outstanding optical properties are widely used in ultrafast photonics. Especially, metal nanomaterials have attracted increasing attention in recent years owing to the surface plasmon resonance that further enhances their nonlinear optical response, making them suitable for generating ultrafast pulses in a wide range of wavebands. Herein, the fabrication and integration processes of typical metal nanomaterials such as gold, silver, and copper, as well as their applications in ultrafast lasers are reviewed. The synthesis methods of metal nanomaterials, which can be divided into dry and wet methods, are first introduced with their characteristics and advantages summarized. Moreover, the integration approaches that are used to incorporate metal nanomaterials into laser cavities are discussed, where sandwich structure based on polymer film and deposition method, as well as evanescent-wave structure based on D-shaped and tapered fiber are demonstrated. Besides, the state of the art of typical ultrafast lasers enabled by metal nanoparticles is systematically reviewed. Finally, current challenges and perspectives on the development of ultrafast photonics enabled by metal nanomaterials are proposed.