As a noninvasive treatment method, photothermal therapy (PTT) has been widely investigated for cancer therapy. In this work, metal-organic frameworks@polymer composites (UiO-66@CyP) with bioimaging and PTT activity were prepared by introducing cyanine-containing polymer (CyP) via multicomponent Passerini reaction in the presence of Zr-based nanoscale metal-organic frameworks (UiO-66). As-prepared UiO-66@CyP not only possesses uniformed size, controllable morphology, and excellent dispersibility in aqueous media, but also indicates strong near-infrared absorption and high photothermal conversion efficiency. Due to these combined merits, UiO-66@CyP appears to be an excellent phototherapy agent for ablation of tumor cells under a low-power laser irradiation and near-infrared fluorescence imaging agent. This work might open up a new avenue to develop multifunctional composites by integrating metal-organic frameworks with carboxyl, aldehyde, and isocyano-containing materials.