Nonconjugated fluorescent polymers are an important class of fluorescent materials for the detection of heavy metal ions. However, the utilization of nonconjugated fluorescent polymer to fabricate film-type detector is mostly limited due to their branched molecular structure. Here in this article, a film-type detector from hyperbranched fluorescent poly(amido amine) (HPAMAM) and polymethyl methacrylate (PMMA) was fabricated through electrospinning to detect cobalt ion in aqueous solution. The HPAMAM/PMMA composite film can respond to Co2+ ions with high sensitivity and selectivity. Moreover, the fluorescence quenching obeys the Stern-Volmer law in a linear range of 1–50 μM. This work provides an effective route to fabricate film-type detectors from nonconjugated fluorescent polymers.