The thirteenth season of the American comedy television series It's Always Sunny in Philadelphia premiered on FXX on September 5, 2018.

[2] In March 2017, following the twelfth season finale in which Glenn Howerton's character was seemingly written off the show, Howerton expressed doubt about his return for the thirteenth season, describing it as "partially a creative and personal decision."

[3] In late April, Kaitlin Olson confirmed Sunny's extended hiatus ahead of the thirteenth season due to the cast's busy schedules.

The site's critical consensus reads, "It's Always Sunny's winning formula keeps the laughs rolling and the stomachs turning in a thirteenth season that's topical, triumphant, and toxic in the best way.

"[16] The finale in particular received praise, with many critics lauding the unexpected emotional and artistic depth of Rob McElhenney's performance.