This study investigates the impact of fiber composition and fabric structure on the liquid absorption and retention performance during pressure of weft-knitted fabrics designed for reusable incontinence products. Twelve fabric samples, made from polyester, polyamide (6.6), and viscose, were knitted in two structures—1 × 1 interlock and 1 × 1 rib—with varying stitch lengths. Key parameters such as porosity, air permeability, liquid absorption capacity (LAC), and retention capacity during pressure (RCDP) were measured and analyzed. Results showed that viscose fabrics demonstrated superior LAC (up to 312%) and RCDP due to their high hydrophilicity, fiber swelling, and porosity. Polyester and polyamide had lower LAC, with polyester performing better due to higher porosity despite its hydrophobic nature. Increasing stitch length reduced fabric density and increased porosity and air permeability, thereby enhancing LAC but decreasing RCDP. Rib structures consistently exhibited higher LAC, while interlock structures offered better RCDP due to smaller, more uniform pores. The findings highlight the importance of optimizing the porous structure by altering knitting parameters and fabric structure to develop reusable absorbent textiles that balance high absorption and retention capacity during pressure.