Curcumin (CCM) is an important molecule for achieving cancer theranostics because CCM is a naturally-occurring biocompatible material that exhibits both anticancer activity and strong fluorescence property that can be used for bio-imaging. However, CCM has never been utilized in clinical trials due to its extremely low water solubility, its rapid hydrolysis in aqueous conditions at neutral pH, and its low cellular uptake into cancer cells. Taking advantage of the strong hydrophobicity, p-conjugated frameworks, and ketone and enol groups that generate hydrogen bonds in CCM, we herein fabricated novel CCM-based biodegradable nanovesicles, which we termed as "curcumisome", through the self-assembly of amphiphilic CCM-poly(ethylene glycol) conjugates in aqueous media to develop multifunctional nanobiomaterials for use in cancer theranostics. A high CCM loading content in the curcumisomes was achieved, and the curcumisomes showed high water dispersibility with improved hydrolysis resistance. Importantly, the curcumisomes were effectively internalized into cancer cells and exhibited strong fluorescence for a long period, which is favorable for cancer cell imaging, although only a small amount of the curcumisomes penetrated into normal cells and showed very weak fluorescence. Moreover, curcumisomes effectively induced apoptosis of cancer cells. Thus, curcumisomes may act as multifunctional nanobiomaterials for the development of CCM-based cancer theranostics.