The disclosure provides apparatus and methods of use pertaining to a bidirectional biomechanical prosthetic finger assembly. One embodiment includes a metacarpophalangeal (MCP) pivot configured for swivelable attachment to a hand of a user, a distal coupler, and an articulation assembly rotatively coupled therebetween. A multiple-finger ring configured to receive a user's residual finger and at least one adjacent finger is disposed upon the articulation assembly, and may be adjusted to a target location based on a length of the residual finger. The articulation assembly is configured to utilize vertical movements of the residual and/or adjacent finger(s) within the multiple-finger ring to articulate the distal coupler within a plane parallel to an x-z plane, and the MCP pivot is configured to utilize lateral movements of the residual finger within the ring to articulate the distal coupler within a plane parallel to an x-y plane. Other embodiments are also disclosed.