With the rapid increase of human exploration and utilization of ocean space, awareness of threats posed by extreme wave events elevates significantly. To protect man-made structures, breakwaters are widely used and they can be classified according to bottom fixed and floating ones. Compared to bottom fixed breakwaters, floating breakwaters can have the advantages such as low cost, easy installation, and environmental friendliness. The relevant technology has not been thoroughly studied yet. Recently, we performed a sequence of preliminary experimental and numerical investigations. The experimental tests were conducted in a wave flume at the Shanghai Jiao Tong University with image processing techniques. The numerical simulations were implemented with a Reynolds averaged Navier–Stokes equation code. We investigated the performance of porous floating breakwaters with different input wave states. In addition, we examined and discussed the wave attenuation performance of floating breakwaters with different moment of inertia and length scale. The results will enhance the scientific understanding and guide the feasibility studies of using floating breakwaters to protect the coast of Asian cities.