On a global scale, new policies and regulations are being proposed to reduce plastic pollution and adopt a new path toward sustainable development. Considering this, the design of composites using green treatments (ultrasound/plasma) and sustainable materials (starch and Agave fibers) was performed. Structural analysis indicated that dual treatment promoted the structural alteration of the superficial lignocellulosic components, hydroxyl groups, and amorphous regions of fibers without incorporating new elements from hexamethyldisiloxane (HMDSO) on their surface. Nevertheless, the treatments provide higher polarity on the fiber surface, promoting stronger secondary bonds between fibers and starch molecules, resulting in starch films with smooth surfaces and better mechanical interlocking as changes in roughness (612 to 499 nm), melting temperature (130 to 146 °C), loss (474 to 1688 MPa) and Young modulus (12 to 202 MPa) indicated. These findings highlight a feasible way to obtain an eco-sustainable reinforcing Agave fiber-filler, suitable to develop starch films for packaging applications. Graphical Abstract