A fully composite modular footbridge has been developed at BUT Brno to serve as a temporary bridge. The modular system (basic length 2.0 m, free width 2.5 m) and the use of composite materials allow for rapid and flexible assembly. This design enables easy adjustment of bridge length based on the number of modules used. The load-bearing structure consists of sandwich FRP wall beams in the longitudinal plane and transversely oriented pultruded profiles, forming the basic “U”-shaped structure module. Each module is supplemented at both ends by stiffening frames to limit horizontal deformations and assist in shear force transfer. Modules are connected by steel plates at the compressed and tensioned flanges. The walking deck is from composite grid with a non-slip surface. A numerical model was developed to predict the behaviour of the fully composite footbridge. Based on the numerical results, the fully composite footbridge with four modules and a total span of 8.0 m was constructed. Experimental verification of static loads was conducted in both vertical and horizontal directions. Vertical loading, aimed at determining the bridge’s vertical stiffness, was applied at three defined levels of surface load. Due to the structure’s size and type, water tanks with a capacity of 1000 litters were used to simulate a uniform surface load. For horizontal loading, a point load was applied at the mid-span of the bridge. The horizontal stiffness was primarily controlled by the joints between the individual modules, and the effect of adding horizontal braces was monitored.