Artificial solid-state nanochannels featuring precise partitions present a highly promising platform for biomarker detection. While the significance of probes on the outer surface (P OS ) has been relatively overlooked in the past, our research highlights their crucial role in biosensing. Furthermore, the contribution of P OS on the bullet-shaped asymmetric nanochannels has not been extensively explored until now. Here, we fabricated a series of bullet-shaped nanochannels, each featuring a distinct asymmetric structure characterized by different tip- and base-pore diameters. These nanochannels were further modified with explicit distributions at the inner wall (P IW ), the outer surface (P OS ), and their combination (P OS + P IW ) for lysozyme sensing. The impact of diameters, structural asymmetry, and surface charge density on the sensing efficacy of P OS and P IW was thoroughly examined through experimental investigations and numerical simulations. P OS demonstrates great individual sensing performance for lysozyme within a broad concentration range, spanning from 10 nM to 1 mM. Furthermore, it improves the sensitivity when combined with P IW , particularly within the nanochannels featuring the smaller base-pore diameter, resulting in a 2-fold increase in sensing performance for P OS + P IW compared to P IW at a concentration of 10 nM. These findings are substantiated by numerical simulations that closely align with the experimental parameters. The contributions of P OS are notably amplified in the presence of smaller base pores and a higher degree of asymmetry within the bullet-shaped nanochannels. These findings elucidate the mechanism underlying the role of P OS within bullet-shaped asymmetric nanochannels and open up new avenues for manipulating and enhancing the sensing efficiency.