This paper presents dynamic characteristics of pressure-fed flexure mechanisms with the additively manufactured internal fluidic channels. Additive manufacturing (AM) technology makes use of the mechanical design flexibility that can effectively control the material distribution in terms of stiffness and damping of the flexures. Five different fluidic channel geometry (circular, semicircular, inverse-semicircular, triangular, and inverse-triangular) with the same cross-sectional area was designed and fabricated inside of one-dimensional cantilever beam (10 × 30 × 100 mm3). Stiffness, damping ratio and natural frequency of each cantilever according to varying air pressure condition from 14.7 psi (atmospheric pressure) to 75 psi were characterized, and at the same time dynamic behaviors of each cantilever were identified by using dynamic signal analyzer. In addition, dynamic characteristics of water-filled flexure mechanism were compared to those of air-filled cases. As a result, the internal channel geometry and filled-in media in the channel have significant influences to determine dynamic characteristics of flexure mechanisms. Such pressure-fed mechanisms can be considered in the first stage of AM flexure design and fabrication processes to adaptively control dynamic behaviors in an easy, convenient and low-cost manner.