Thermoplastic polyaryletherketones (PAEKs) exhibit excellent mechanical properties and fluid stability, but their glass transition temperatures (Tg) are low and their all-aromatic nature makes processing challenging. We will present a synthetic route toward phenylethynyl-functionalized hyperbranched PAEKs (hbPAEKs) (Tg = 151 °C) that can be cross-linked to form flexible films with high Tg's (187-237 °C) and good mechanical properties (E′ = 4 GPa, σ = 44 MPa, and ϵ = 1.76%). After cross-linking, the films are amorphous, easy to handle, and insoluble. We will report on the melt rheology of the hbPAEK precursors, with and without reactive phenylethynyl-reactive functionalities, and the thermomechanical characteristics of thin cross-linked films using dynamic mechanical thermal analysis, differential scanning calorimetry, and tensile testing. We believe that our findings can be extended to other all-aromatic structural and functional polymer architectures that are otherwise impossible to process.