Epitaxial liftoff is an alternative to lattice‐mismatched heteroepitaxial growth. Multilayer AlxGa1−xAs epitaxial films are separated from their growth substrates by undercutting an AlAs release layer in HF acid (selectivity ≳108 for x≤0.4). The resulting AlxGa1−xAs films tend to bond by natural intermolecular surface forces to any smooth substrate (Van der Waals bonding). We have demonstrated GaAs thin‐film bonding by surface tension forces onto Si, glass, sapphire, LiNbO3, InP, and diamond substrates, as well as self‐bonding onto GaAs substrates. In transmission electron microscopy the substrate and thin‐film atomic lattices can be simultaneously imaged, showing only a thin (20–100 Å) amorphous layer in between.