Elastic recovery is the ability of a stretched material to return to its original size, a quality crucial for textile products. Knitted textiles made from only natural fibers, such as cotton, have poor elastic recovery. Therefore, yarns made from elastane, a flexible synthetic copolymer, are commonly embedded into these fabrics during the knitting process. While elastane improves elastic recovery, it limits the ability of natural fiber textiles to be recycled or decomposed. This paper proposes a sustainable alternative to elastane-blended textiles by 3D printing flexible compostable filaments onto natural knitted textiles. The 3D-printed structures improve elastic recovery and allow complete degradation of the textiles in industrial compost facilities. To test the impact of 3D printing structures on elastic recovery, a square grid pattern with varying thicknesses was 3D printed on 100% cotton knit fabrics. Three compostable flexible filaments were printed onto the same fabric using a special jig containing a thin foam sheet underneath the textile to enhance the adhesion of the printed material. All samples were tested using a Continuous Rate of Extension (CRE) machine. After selecting the best-performing material and knit structure, we 3D printed different auxetic patterns to examine the effect of the geometry on the elastic recovery. The results show that re-entrant double arrowhead, honeycomb, and sinusoidal ligament structures exhibited the lowest ratio of deformation to elongation. This research aims to contribute to the fields of textiles and additive manufacturing by finding sustainable ways to create elastic textiles using 3D printing.