Season 0 of 999: On the Front Line premiered on June 21, 2020.

Season 1 of 999: On the Front Line premiered on September 13, 2017.

Season 2 of 999: On the Front Line premiered on September 23, 2018.

Season 3 of 999: On the Front Line premiered on August 25, 2019.

Season 4 of 999: On the Front Line premiered on February 2, 2020.

Season 5 of 999: On the Front Line premiered on January 31, 2021.

Season 6 of 999: On the Front Line premiered on August 30, 2021.

Season 7 of 999: On the Front Line premiered on November 7, 2021.

Season 8 of 999: On the Front Line premiered on September 25, 2022.

Season 9 of 999: On the Front Line premiered on January 16, 2023.

Season 10 of 999: On the Front Line premiered on January 30, 2024.

Season 11 of 999: On the Front Line premiered on January 12, 2025.

Season 12 of 999: On the Front Line premiered on May 4, 2025.