A new, bifunctional recombinant protein was expressed as the fusion product of human elastin‐like polypeptide (HELP) and the bilirubin‐binding protein UnaG. The engineered product displays both the HELP‐specific property of forming a functional hydrogel matrix and the UnaG‐specific capacity of emitting green fluorescence upon ligand binding. The new fusion protein has been proven to be effective at detecting bilirubin in complex environments with high background noise. A cell culture model of the stress response, consisting of bilirubin released in the cell culture medium, was set up to assess the bilirubin‐sensing properties of the functional matrix obtained by cross‐linking the HELP moiety. Our engineered protein allowed us to monitor cell induction by the release of bilirubin in the culture medium on a nanomolar scale. This study shows that elastin‐like protein fusion represents a versatile platform for the development of novel and commercially viable analytical and biosensing devices. A new, bi‐functional protein was obtained by fusing the Human Elastin‐like Polypeptide (HELP) and the UnaG bilirubin‐specific binding protein. In this study, the Authors show that this new expression product formed a solid‐state 3D matrix that retained the property of binding bilirubin with high affinity even in complex multicomponent biological mixtures. Fluorescence interfering signals were removed by simply changing the soaking medium of the matrix. Nanomolar bilirubin concentrations in microwells could be detected by using a standard multiplate fluorimeter.However, if the Editor decided that it has to be shortened, we agree with that proposed in this version.