Limitations to the scaling of sodium alginate (SA) fibers by wet spinning and for commercial applications are the high spinning dope viscosity and low fiber mechanical performance. In this study, the viscosities of SA spinning dopes dramatically reduced to an order of magnitude lower while the maximum spin draw ratio increased from 1 to 6 as sodium polyacrylate (PAAS) loading increased up to 20 %. However, distinct to a simple plasticizing effect, adding appropriate amount of PAAS strengthens the mechanical properties of fully drawn fibers, through the formation of new physical crosslinks with SA. Fibers having the tenacity of ∼0.6 cN/dtex, modulus of ∼37 cN/dtex, strain at break of ∼7 % and toughness of ∼4 J/g were achieved with 15 % PAAS loading. Therefore, the PAAS addition has dual-effects in SA fiber wet spinning: to modify the rheology of the SA spinning solution and to strengthen the wet-spun SA fibers for textile applications.