We designed and synthesized two heptamethine cyanine-based theranostic probes that aimed to target COX-2 in cancer cells. One is I-IR799-CXB, in which I-IR799 is conjugated to the COX-2-specific inhibitor, celecoxib, and another is I-IR799-IMC, where the non-selective COX inhibitor, indomethacin, was used. I-IR799 is a heptamethine cyanine derivative that can be activated by near-infrared light for photodynamic therapy (PDT) purposes. I-IR799-CXB and I-IR799-IMC were tested for their cancer-targeting capacity and photodynamic efficiency toward hepatocellular carcinoma (HepG2) cells relative to normal liver cells, alpha mouse liver 12 (AML12) cells. Interestingly, after conjugation, I-IR799-IMC exhibited better tumour targetability and PDT efficiency than I-IR799-CXB.