The youngest player to score a century in T20Is is G Mckeon.
According to this source, G Mckeon scored a T20I century at the age of 18 years and 280 days. Here's a list of the youngest players to achieve this feat:
| Rank | Player | Age at Match Date |
|---|---|---|
| 1 | G Mckeon* | 18 years 280 days |
| 2 | Kushal Malla* | 19 years 206 days |
| 3 | M Levitt* | 20 years 255 days |
| 4 | Hazratullah Zazai* | 20 years 337 days |
