We explored the effect of 3 mg/kg of caffeine supplementation on the cognitive ability and shooting performance of elite e-sports players. Nine e-sports players who had received professional training in e-sports and had won at least eighth place in national-level e-sports shooting competitions. After performing three to five familiarization tests, we employed a single blind, randomized crossover design to divide participants into caffeine trial (CAF) and placebo trial (PL). The CAF trial took capsules with 3 mg/kg of caffeine, whereas the PL trial took a placebo capsule. After a one-hour rest, the Stroop task, the visual search ability test, and the shooting ability test were conducted. The CAF trial’s performance in the Stroop task in terms of congruent condition (
P
 = 0.023) and visual search reaction time with 20 items (
P
 = 0.004) was significantly superior to those of the PL trial. In the shooting test, the CAF trial’s kill ratio (
P
 = 0.020) and hit accuracy (
P
 = 0.008) were significantly higher, and the average time to target (
P
 = 0.001) was significantly shorter than those of the PL trial. Caffeine supplementation significantly improves e-sports players’ reaction times and shooting performance.