MrIC is a recently described selective agonist of endogenously expressed α7 nAChR. In this study, we further characterise the pharmacological activity of MrIC using Ca2+ imaging approaches in SH-SY5Y cells endogenously expressing α7 nAChR and demonstrate that MrIC exclusively activates α7 nAChR modulated by type II positive allosteric modulators, including PNU120596. MrIC was a full agonist at PNU120596-modulated α7 nAChR compared with choline, albeit with slower kinetics compared to choline, but failed to elicit a Ca2+ response in the absence of PNU120596. Interestingly, the NMR structure of MrIC showed a typical 4/7 α-conotoxin fold, indicating that its unusual pharmacological activity is likely sequence-dependent. Overall, our results suggest that MrIC acts as a biased agonist that can only activate α7 nAChR modified by type II allosteric modulators, and thus represents a valuable tool to probe the pharmacological properties of this important ion channel.