The episode is set in a beach resort town named San Junipero, where the introverted Yorkie (Mackenzie Davis) meets the more outgoing Kelly (Gugu Mbatha-Raw).

"San Junipero" was the first episode written for series three of Black Mirror; initial drafts were based on nostalgia therapy and designed as a 1980s period piece.

The episode received critical acclaim, with particular praise for Mbatha-Raw's and Davis's performances, its plot twist, its visual style, and its uplifting tone, which is atypical for the series.

San Junipero is revealed to be a simulated reality where the deceased can live, and the elderly can visit, all inhabiting their younger selves' bodies in a time of their choice.

Yorkie wishes to be euthanised to live in San Junipero permanently, but her family objects; she intends to marry Greg so that he can consent for her.

[4] Alongside series three episode "Nosedive", "San Junipero" was first shown in 2016 ahead of its Netflix release at the Toronto International Film Festival.

[8] Brooker initially envisioned an episode in which technology is used to investigate whether an afterlife exists,[6] thinking of the genres of horror and supernatural fiction.

[11] Brooker and executive producer Annabel Jones felt that their concept of virtual consciousness, established in the episode "White Christmas", had more potential.

[10] He then recalled the 2010 BBC series The Young Ones, in which older celebrities live in a home decorated in the fashion of the 1970s and find themselves rejuvenated by the setting.

[8] In the initial draft, the love story was about a heterosexual couple, but Brooker changed it to give the episode an extra resonance, as same-sex marriage was not legal in 1987.

[13] He has said that having a twist makes the writing process easier, as "when you know that 85 percent of what's happening you can't reveal till later on, it actually sort of narrows your options in a useful way".

[14] One draft of the episode contained a scene where Kelly visits a kindergarten in San Junipero, full of children who had died, but it was removed because "it was too sad and too poignant of a note to hit in that story".

[13] Brooker told The Daily Beast that in the rough treatment, the episode ended with the scene where Kelly and Yorkie meet in the hospital, but "when I sat down to actually write it, I was enjoying it so much that I thought, No, I'm going to keep going!

[10] The ending came about when Brooker heard "Heaven is a Place on Earth" off a streaming playlist while writing the script, and wanted to license the song for the episode.

[19] Some songs, such as Belinda Carlisle's "Heaven Is a Place on Earth" and the Smiths' "Girlfriend in a Coma", hint at the episode's plot twist,[20] as do arcade games Time Crisis and The House of the Dead.

[22] Gugu Mbatha-Raw, who plays Kelly, had heard of the show but not seen it when she received the script, though she did watch the series two episode "Be Right Back" before the shoot.

[10] The episode was filmed in 15 days across a three-week period,[10][23] with shooting split equally between London for most of the interior shots, and Cape Town, South Africa, for most external scenes.

He noted that whilst shooting Kelly and Yorkie's argument on the beach, an "incredible mist rolled in from the ocean", which caused difficulties but led to "some really lovely texture".

For example, the choice of the song "Girlfriend in a Coma", and the use of the arcade games Time Crisis and The House of the Dead allude to the true reality of the episode.

[10] More overtly, Yorkie reacts viscerally to seeing a car accident in an arcade game, an element that Brooker was surprised was not picked up by viewers earlier.

[4] Mat Elfring of GameSpot described it as the only episode with "warmth to it",[40] and Digital Spy reviewer Morgan Jeffery called it the "most upbeat and positive".

[44] The episode subverts a common trope in television of killing off lesbian characters: though Kelly and Yorkie die, they have a happy ending.

[45] Some felt its Emmy Awards marked a cultural shift in relation to portrayal of lesbianism,[46] or proof of concept that works dealing with LGBT characters need not be tragic.

[50] At the time of its release, "San Junipero" was very popular among fans,[a] which has been attributed to its emotive presentation of a love story with a happy ending.

Critics' consensus on the website reads, "Black Mirror delivers an uncharacteristically uplifting and enjoyable ending in "San Junipero", an especially bright and sweetly surprising episode that benefits greatly from its vibrant lead performances.

Robbie Collin of The Daily Telegraph criticised the characters' dialogue but praised that the ending is emotional due to Mbatha-Raw's "vivacity and conviction".

[64] However, Andrew Wallenstein of Variety criticised Mbatha-Raw and Davis for an inability to "pack the emotional punch" needed for the episode to stand out.

Corey Atad of Esquire and Tim Goodman of The Hollywood Reporter both opined that the story would leave viewers in tears,[62][66] and Adam David of CNN Philippines cried whilst watching it.

[75] Additionally, Proma Khosla of Mashable ranked the 22 Black Mirror instalments excluding Bandersnatch by tone, concluding that "San Junipero" is the second-least pessimistic episode of the show after "Hang the DJ".

[11] In an interview with NME, Brooker mentioned that some ideas for the episode were later removed, such as a scene with a kindergarten in San Junipero that "felt like a whole world in and of itself".