Polyethylene terephthalate (PET, polyester) capillary-channeled polymer (C-CP) fibers were employed as the base structure for surface modification to provide a sorbent for solid phase extraction (SPE) of aqueous cations. Surface functionalization with polyacrylic acid (PAA) was achieved using a “grafting to” approach, yielding a stable sorbent that has the potential of being employed over a large range of pH values and a variety of sample matrices. PAA was chosen for surface modification because the repeating acrylic acid monomeric unit, which contains a carboxylic acid, has the ability to bind metal ions. In a micropipette-tip SPE format, these PAA-functionalized C-CP fibers showed the ability to efficiently bind several metals (Cu²⁺, Cu⁺, Ni²⁺, Fe³⁺, UO₂²⁺), while elution could be achieved with extremely low concentrations of hydrochloric acid (1 ml of 0.005%), resulting in overall recoveries of greater than 88%. A single tip was carried throughout the entire study as a control, and showed overall recoveries averaging 96% over the course of 19 extraction experiments and a 12-month period, demonstrating the chemical stability of the sorbent material, and suggesting the potential of the C-CP fiber SPE tips to be used multiple times.