A pet restraint harness system for use in a vehicle may be installed in a rear or front passenger seat. The restraint system includes a harness fastened about the pet and a restraint framework fastened about the seat and, in some configurations, to manufacturer latch points provided in the vehicle. The restraint framework includes a vertical strap positioned against the seatback and one or more lateral straps attached to the vertical strap to resist lateral movement, vertical movement, or both. One end of the vertical strap and the lateral straps may attach to the manufacturer latch locations. Alternatively, ends of the vertical and lateral straps may attach to each other about the seat. At least two restraining straps are attached to the vertical strap, the lateral straps, or among the combination of both. The restraining straps are configured to attach to an animal's collar, to a harness, or both.