This is the first time to report a facile strategy to fabricate galactoglucomannan-based latex with highly transparent, hydrophobic and flexible characteristics by combining etherification with subsequent emulsion polymerization. The allylated galactoglucomannans (A-GGM) and galactoglucomannan-based latexes (GGM-L) were prepared and their chemical structure, substitution degree, molecular weight, conversion rate, particle size and zeta potential were characterized by ATR-FTIR, 1HNMR, quantitative 13CNMR, HP-SEC, HPLC and zeta-sizer nanometer analyzer, respectively. Furthermore, the effects of substitution degree on film surface roughness and homogeneity, water vapor permeability (WVP) and thermal stability were evaluated by AFM, SEM, WVP and TGA, respectively. The optimal GGM-L film exhibited 91.3% transmittance and 0.43% haze, 117° water contact angle, 31.2% elongation at break and 30.9 MPa ultimate tensile stress. The bio-based content of the GGM-L may reach about 99 wt%, which provides a promising avenue for polyolefin-based latex replacement for paper and paperboard applications.