Creating a secure and comfortable linkage between the residual limb and prosthetic socket is a critical factor for successful rehabilitation, including ambulation and other activities of daily living. Unwanted rotation within the socket can be a clinical problem for prosthesis users. One way of addressing issues experienced with transverse plane control of the socket may be through the increase of friction interface forces. It has been proposed that friction at the residual limb/socket interface may be increased by adding texture to interface components. Three-dimensional (3D) printing may be used to fabricate sockets with texture patterns added to the inner socket surface. The aim of this study was to develop a mechanical testing protocol to investigate the effects of socket texturing on transverse plane rotation of the socket on a mock residual limb under two suspension conditions: passive suction and active vacuum. Sockets with 14 different texture patterns were fabricated using the Squirt-Shape 3D printer. Textured sockets were tested and compared to an Original Squirt-Shape (OSS) socket and a smooth thermoformed socket. Sockets were fitted with a mock residual limb and bi-axially loaded to compression of 350 N with simultaneous rotation (2.5, 5 and 7.5) using a custom rotation assembly attached to a uniaxial hydraulic material testing system. There was a statistically significant three-way interaction between suspension, angle and texture (p < 0.0005). Torques between textured and reference sockets, for all rotation angles and both suspension conditions, were significantly different (p < 0.0005). By applying newly developed rotation testing protocols, it was demonstrated that some textured socket patterns significantly increased torque (increased resistance against unwanted rotation) in the transverse plane compared to both OSS and smooth sockets especially for passive suction. Rotation testing of sockets may provide insight into socket design to improve suspension in the transverse plane.