Disclosed are a millimeter-wave end-fire circularly polarized antenna and a wireless communication device. The antenna comprises a first dielectric substrate and a substrate integrated waveguide. A radiating element is arranged on the first dielectric substrate. The lower layer of the first dielectric substrate serves as a metal floor, and a slot is provided at the central position of the metal floor. The substrate integrated waveguide is vertically arranged. The upper end of the substrate integrated waveguide is connected to the slot, and forms a T-shaped structure together with the first dielectric substrate. The lower end of the substrate integrated waveguide serves as a feeding inlet. The T-shaped structure of the present invention forms a 3D structure; the present invention has the advantages of a compact structure, a low profile, and low cost; and a feeding element is only formed by the substrate integrated waveguide, such that the antenna can be integrated with a main board more easily, and at the same time, the antenna has the characteristics of a high impedance bandwidth, a high in-band axial ratio bandwidth, a high gain, a stable directional diagram, a good circular polarization directivity, etc., and can be applied to devices for wireless communication, such as millimeter-wave 5G mobile communication.