Liberty High School’s senior class is preparing for graduation, but of course before they can actually say goodbye to each other and their school, they will have to keep a dangerous secret buried, as well as face “heartbreaking choices” that may impact their futures forever.
| "Winter Break"
|The police question Tyler about the guns, leaving the friends rattled. Winston transfers to Liberty High after getting expelled from Hillcrest.|
| "College Tour"
|After an incident at school, Clay thinks someone's trying to set him up. Zach and Clay land in hot water during a college tour.|
| "Valentine's Day"
|As the school gears up for the Love Is Love dance on Valentine's Day, disturbing phone calls keep Clay from getting in the spirit.|
| "Senior Camping Trip"
|Clay is forced to confront his anxiety on the senior camping trip as a suspicious email threatens to turn the friends against each other.|
| "House Party"
|The Jensens make the boys take a drug test. When the Liberty parents learn about an upcoming party, Clay suspects that they're tracking the students.|
|The school goes into lockdown, and Clay, Tony and Justin worry about Tyler's whereabouts. Zach gets high with Winston and confides in him something he shouldn't.|
| "College Interview"
|Clay's mental health continues to decline as the friends wrestle with difficult emotions during their college admissions interviews.|
|The police reveal to Clay and Tony that they have been using Tyler as an informant to catch illegal gun dealers. Diego accuses Justin of killing Bryce. Clay tells his therapist he is ready to confess all his secrets.|
|When the dean begins a new investigation and threatens to cancel prom, the friends decide to confide in their parents... but not about everything.|
|Strengthened by the struggles they've endured, the friends say goodbye to high school and look forward to the future in an emotional series finale.|
- Production was already underway as of August 1, 2019 and filming ended December 19, 2019. 
- Brenda Strong, who portrays Nora Walker, directed the fifth and sixth episode of this season.
- The global pandemic COVID-19 did not affect the production process of this season.
- This season, Gary Sinise (Dr. Robert Ellman), Jan Luis Castellanos (Diego Torres), Tyler Barnhardt (Charlie St. George), Deaken Bluman (Winston Williams), and Mark Pellegrino (Deputy Standall) were added to the main cast.
- This makes Season 4 have the most main cast members out of all seasons.
- This is the first season to feature Diego Torres.
- Nation Editions reported "The end of the third season concludes the Bryce Walker mystery. The group dodges the bullet with the help of Annie [sic], who artfully blames Monty. Everyone celebrates at Monet [sic] and wants things to improve from now on. But their problems are not yet over. There are flaws in their stories that will require clarification. He has made mistakes that will come back to haunt him. The setting for season 4 of ’13 Reasons Why ‘is set by two events."
- Brian Yorkey stated in an interview that this season would only consist of 10 episodes: "It served the story better, and 10 episodes ended up being the sweet spot for us. I think 10 episodes is a nice length for a season. I was adamant going into season 2 that it had to be 13 because the show's called 13 Reasons Why and if I'm a young viewer, I'm like, "13 reasons why but there's only 10 episodes." But at this point, heading into season 4 it was like, "We've given them 39 reasons why (episodes in total) at least, so I feel like we can say, yes the show is still called 13 Reasons Why, this season is 10 episodes." It's the right number, you'll see that when we get to the end."
- This is the shortest season, having only 10 episodes, whereas all previous seasons contained 13 episodes each.
- This is the first and only season that doesn't have an official soundtrack or aftershow.
- See also: 13 Reasons Why (Soundtrack)#Season 4
|“||Season 4 is a very different season. Each of the seasons has been unique, but Season 4 is more of a psychological exploration of what happens to friends when they’re forced to keep a secret. What happens to people when their guilt and their shame starts to eat them from the inside out. Season 3 was a whodunit. Season 2 was the trial. It was about the law and justice. Season 1 was about the mystery surrounding one particular individual. They’ve each had their own unique flavors.
Nora Walker may or may not be part of that complexity. I think there’s ample room for her to enter into it, particularly in terms of Ani, since Ani was part of her household and is the line to Bryce. But we’ll see! I can’t really say how much or how little she’ll be involved.
|— Brenda Strong in an interview with Pop-Culturist|
|“||We wanted to end the series hopefully, but we wanted it to be earned hope. The series was born in darkness and as is often pointed out, it is a dark series, but we have always tried to infuse it with hope and with humor where we can, and we wanted to end on a note of hope that was earned and that was not forced and also not overly sunny in a way that wouldn't be consistent with what had gone before. The other word that comes to mind, along with hope, is survival because everything comes after our ability to survive our hardest moments and our ability to keep moving and to stay alive for all the brighter things that life has in store for us. This show started with Hannah Baker not being able to do that, and we wanted to end by seeing so many of our characters able to do that, to face the real darkness, and to come out the other side into the light. That's what we wanted and I think and hope we achieved that.||”|
|— Brian Yorkey about how they wanted the series to end speaking to Entertainment Weekly |
- Variety — "’13 Reasons Why’ Renewed for Fourth and Final Season, Season 3 to Launch in August" (August 1, 2019)
- Digital Spy — "13 Reasons Why season 4: Release date on Netflix, cast, plot and everything you need to know" (May 21, 2020)
- Variety — "Netflix Announces ’13 Reasons Why’ Final Season Premiere Date" (May 11, 2020)
- RadioTimes — "When is 13 Reasons Why season 4 released on Netflix? Cast, filming and spoilers" (December 4, 2019)
- Ross Butler (@rossbutler) — Goodbye 13 Reasons Why
- Instagram (instagram.com) –– Brenda Strong (@strongbrenda) Brenda Strong about directing for 13 Reasons Why
- Golden Globe Awards — "Jan Luis Castellanos Joins “13 Reasons Why”" (April 20, 2020)
- Nation Editions — "13 Reasons Why Season 4: Potential Deaths And Other Major Spoilers" (March 13, 2020)
- Entertainment Weekly — "13 Reasons Why boss on ending the series and what to expect from season 4" (Retrieved May 12, 2020)