Terahertz (THz) waves, situated between microwaves and infrared radiation, own strong penetration capabilities, low photon energy, and high biological safety, demonstrating significant application potential in fields such as material detection, biomedicine, communications, and astronomy. However, the advancement of THz technology still encounters numerous challenges, particularly in the development of efficient radiation sources, detectors, and ultra-sensitive detection and modulation devices. Polaritons, which are quasi-particles formed by the coupling of light with electrons and phonons in matter, can enhance the interaction between light and matter in the THz frequency range, offering promising solutions to the bottlenecks in THz optoelectronic devices. Low-dimensional materials, such as graphene, Bi₂Se₃, and Ag₂Te, with their nanoscale thickness, tunable carrier concentration, and rich lattice structures, exhibit polaritons with low loss, high optical field confinement, enhanced optical fields, and high tunability. These characteristics provide additional opportunities to address the challenges in the field of THz science and technology. Since its discovery in 2004, graphene has been shown to support plasmon polaritons from massless Dirac carriers. Using methods like gate electrodes and chemical doping, these polaritons can operate in the IR to THz range. In 2011, researchers first measured plasmonic resonances in far-IR to THz frequencies in graphene ribbons, confirming their high field confinement and tunability. Later, in 2016, THz near-field microscopy with photocurrent detection enabled real-space imaging of graphene acoustic plasmon polaritons (APPs), revealing their superior field localization and compression over optical modes. Leveraging APPs enables further exploration of non-local quantum effects (Fig.5). Dirac carriers are not exclusive to graphene but are also widely present in low-dimensional topological insulator materials, such as Bi₂Se₃. THz plasmon polaritons in Bi₂Se₃ were first reported in 2013 and was claimed from the Dirac carriers. In fact, the plasmon polaritons in Bi₂Se₃ may be also contributed by bulk carriers and optical phonons, in addition to Dirac carriers. In 2022, researchers achieved real-space imaging of THz polaritons in Bi₂Se₃ and revealed that the polaritons arise from the combined contributions of bulk-doped carriers, Dirac carriers, optical phonons, and a two-dimensional electron gas induced by surface state band bending (Fig. 6). In contrast to the in-plane isotropic plasmon polaritons described above, recent studies have shown that WTe₂ can support far-IR in-plane hyperbolic plasmon polaritons (Fig.7), which exhibit extremely large plasmon wavevectors, resulting in exceptionally high optical field localization and optical density of states (Fig.7). More recently, researchers using terahertz scattering-type scanning near-field optical microscopy discovered that Ag₂Te can support in-plane anisotropic plasmon polaritons. They quantitatively measured the plasmon dispersion using APPs, demonstrating that APPs can not only enhance the localization and compression of THz fields but also improve the propagation quality of the polaritons. Compared to plasmon polaritons, phonon polaritons exhibit significantly lower losses. To date, materials such as α-MoO₃ and α-GeS have been identified as supporting THz phonon polaritons. Specifically, α-MoO₃ has been found to sustain in-plane hyperbolic phonon polaritons within the frequency range of 7.8 to 11.7 THz (Fig. 8), with an impressive polariton lifetime of up to 9 ps. Similarly, α-GeS supports anisotropic phonon polaritons in the THz range (6.1 to 9.5 THz), characterized by long lifetimes and high Q-factors. Significant progress has been made in modulating low-dimensional material polaritons using strategies like twist-angle engineering, doping, and polarization control. For example, in α-MoO₃, adjusting the interlayer twist angle triggers a topological shift from hyperbolic to elliptic polaritons, creating non-diffracting, directional channel modes (Fig.9). In WTe₂, molybdenum doping changes phonon polariton dispersion from elliptic to hyperbolic (Fig.9), while controlling the polarization angle of incident light induces a similar transition in plasmon polaritons due to polarization-dependent surface resonance (Fig.9).This article reviews recent progress in THz polariton photonics in low-dimensional materials, highlighting their exceptional properties like high field confinement, near-field enhancement, strong light absorption, and tunability, which hold great promise for THz optoelectronic devices. While significant advances have been made, many questions remain, and new research opportunities are emerging. Future work will focus on exploring diverse THz polariton systems, such as Cooper pair and magnon polaritons, to uncover new phenomena and applications. It will also develop advanced modulation techniques for precise control and design polariton-based devices like ultra-sensitive sensors and room-temperature photodetectors, addressing current THz technology challenges.