Thermosensitive and imaging-traceable materials with fine-tunable lower critical solution temperature (LCST) around body temperature are highly valuable in biomedicine. However, such materials are rare because it is challenging to fine-tune the LCST and incorporate suitable imaging modalities. Herein, peptidic monodisperse polyethylene glycol (M-PEG) "combs" with fine-tunable LCST, "hot spot" fluorine-19 magnetic resonance imaging (19F MRI), thermoresponsive fluorescent imaging, and drug loading ability were developed through accurately programming their structures during solid phase peptide synthesis (SPPS). The easy availability, structural accuracy, biocompatibility, and versatility provide the M-PEG "combs" with promising prospects as thermoresponsive and imaging-traceable biomaterials for controlled drug delivery.