Gelatin methacryloyl (GelMA) is among the most widely used bioinks because it retains the cell-adhesive and protease-sensitive motifs of gelatin and photo-crosslinks on demand. At printable concentrations, however, its viscosity is governed by the gelatin coil–helix transition near ambient temperature, so ink rheology becomes a steep function of print-head temperature and extrusion is difficult to control. Here we report a physically blended biomaterial ink in which microwave-synthesized GelMA (10% w/v) is combined with mucilage extracted from chia (Salvia hispanica L.) seeds at 0.5%, 1%, and 2% (w/v) and photo-crosslinked with 0.3% (w/v) lithium phenyl-2,4,6-trimethylbenzoylphosphinate under a 395–480 nm curing light. ¹H NMR gave a degree of methacrylation of 81.9% for the microwave-synthesized GelMA, determined from consumption of the lysine methylene resonance against an aromatic internal reference. The principal finding is thermal: chia mucilage decouples ink viscosity from temperature. Pristine GelMA lost a factor of 3838 in viscosity between 15 and 45 °C and 63% of its remaining viscosity per degree at the 30 °C print head, whereas the 1% and 2% blends lost only 49- and 41-fold overall and 32% and 15% per degree. The mucilage itself is nearly athermal (258 → 186 mPa·s over the same range), identifying it as the component responsible. Mechanical reinforcement, by contrast, is not a dose response but a threshold effect. Relative to pristine GelMA (55.7 ± 5.8 kPa), 0.5% chia gave a modestly lower compressive modulus (42.6 ± 6.2 kPa) that did not reach significance (P = 0.056), whereas 1% and 2% raised it 17.5- and 30.0-fold (974.8 ± 101.3 and 1671.0 ± 173.8 kPa; P = 0.004). Scanning electron microscopy showed a fibrous polysaccharide network that is sparse and discontinuous at 0.5% and becomes continuous between 0.5% and 1% (w/v), and we interpret the mechanical threshold as rigidity percolation of this network — an interpretation consistent with the microstructure rather than a mechanism established by it. Fourier-transform infrared spectroscopy showed dose-dependent growth of the pyranose C–O–C and carboxylate bands together with a broadened O–H/N–H envelope, indicating hydrogen bonding between the mucilage and the gelatin amide groups, while X-ray diffraction confirmed that the mucilage remains amorphous and well dispersed. Filament geometry measured across nine pressure–speed combinations gave optimal spreading ratios of 1.158 for GelMA, 1.164 for the 1% blend and 1.016 for the 2% blend. Chia mucilage therefore acts less as a stiffener than as an agent that decouples ink viscosity from temperature, widening the thermal processing window of GelMA at low cost from a renewable plant source.  Because no cell-laden printing or cytocompatibility assay was performed, the cell-free formulations described here are termed biomaterial inks rather than bioinks, following the consensus biofabrication nomenclature; the study establishes the rheological and engineering foundation for subsequent cell-laden translation.