In this paper, a symmetric single-sided vibro-impact nonlinear energy sink (SSSVI NES) is introduced to the shock response suppression of a cantilever beam. The equations of motion of the system are derived. The modal test of the cantilever beam is carried out to verify the correctness of the assumption of the Euler–Bernoulli beam. The SSSVI NES is designed based on the modal test results. An experimental study is performed to validate the response suppression performance of the SSSVI NES on the beam under shock excitation. The time history of the acceleration response, wavelet spectrum, and peak response in the frequency domain are all examined. Both simulation and experimental results show that SSSVI NES can effectively suppress the shock response of a cantilever beam.