Mimosa tenuiflora (Willd.) (MT) Poir. is an underutilized plant specie since its wood is mostly used for energy production. Nonetheless, the bark from this forest plant has a high amount of tannins and other valuable compounds. Tannins have high worldwide importance and, because of that, there is an increasing number of researches on biorefinery systems aiming at maximizing their exploitation. The present study evaluated tannins extracted from the MT bark and their use for producing wood adhesives. Three types of powdered tannins were extracted using different solvents: a pure aqueous solution, a 5% sodium hydroxide (NaOH) aqueous solution, and a 5% sodium bisulfite (NaHSO3) aqueous solution. Also, distilled water, wheat flour, and formaldehyde were used as a solvent, a glue extender, and a catalyst, respectively. These adhesives were applied for bonding pine wood joints and their shear strengths were determined. All the MT-based adhesives showed high viscosities and, if compared to each other, yielded glue lines with similar shear strengths and similar shear deformations. That tannin-based glue incorporated with the tannin extracted using NaOH/NaHSO3 stood out and yielded a similar bonding performance compared to a commercial adhesive applied as a positive control.