Tellurium nanoparticles have attracted considerable attention for their optoelectronic properties and biological activities; however, research on their enzyme-like activities remains relatively limited. To synthesize novel tellurium nanozymes and explore their potential application in the detection of mercury ions (Hg2+), Pu''erh infusion-tellurium nanoparticles (PI-TeNPs) were prepared by reducing sodium tellurite with vitamin C, using an aqueous extract of Pu''erh tea as a soft template. The basic characteristics of the nanoparticles were characterized by atomic force microscopy and other techniques. The specific triggering effect of Hg2+ on the oxidase-like activity of PI-TeNP nanozymes was investigated, reaction conditions were optimized, catalytic kinetics were analyzed, and the catalytic mechanism was elucidated. Subsequently, a novel nanozyme sensing method for the detection of Hg2+ in aqueous systems was constructed using PI-TeNPs as colorimetric probes. The results showed that spherical PI-TeNPs with uniform particle size (approximately 8.8 nm) and good dispersibility were successfully synthesized. Hg2+ could specifically trigger the oxidase-like activity of PI-TeNP nanozymes, with a Michaelis constant (Km) of 0.8947 mmol·L-1 and a maximum reaction rate (Vmax) of 8.7719×10-8 mol·(L·s)-1. The oxidase-like catalytic effect was exerted through the formation of HgTe via the binding of Hg2+ with PI-TeNPs, generating singlet oxygen (1O2) and hydroxyl radicals (·OH). Utilizing this characteristic, PI-TeNP nanozymes were used for the detection of Hg2+ in a concentration range of 12.5 to 100.0 μmol·L-1, with a detection limit of 10.77 μmol·L-1. The spiked recoveries of Hg2+ in tap water, purified water, and lake water ranged from 96.30% to 105.68%, with a relative standard deviation (RSD) less than 4.01%. This study provides a new template for the green synthesis of tellurium nanoparticles and a novel method for the rapid screening of Hg2+ in water environments.