The Musical is known for characters suddenly breaking out into song, which audiences will suspend their suspension of disbelief as characters sing their hearts out in exposition. There are some musicals that will occasionally keep things more grounded and have some or all the songs, take place within the context of the story, with a justified explanation. Such explanations usually are that they're performances for other people, in front of a crowd, etc. These works are usually both musicals and Music Stories as they're about music training and performance, and the songs used still convey the character's feelings and motivations as well as exposition.
This does not cover the "All In The Character's Head"-type of musical as covered by the Musical World Hypotheses.
Film - Animated
- The Barbie films Barbie & The Diamond Castle and Barbie In Rock N Royals are this.
- Coco: Every song is performed in-universe, at concerts, a talent competition, or to just practice.
- My Little Pony: Equestria Girls Rainbow Rocks stands out from the other EG films because it's entirely Diegetic; all of the songs are performed by the various bands, as rehearsals, performances, the Mind-Control Music set up courtesy of the Dazzlings, and a musical battle in the climax.
- Sing has nearly all of the songs take place on stage for a concert. The others are for auditions, and two characters sing to themselves in private.
Film - Live Action
- In the 1972 film version of Cabaret, all the musical numbers are in-universe performances at clubs or restaurants, most of them at the Kit Kat Club cabaret. (The original stage musical had non-diegetic songs as well, but they were left out of the film to keep it on a more realistic level.)
- Camp (2003)'s musical performances all take place In-Universe, which makes sense as it takes place at a performance arts summer camp.
- The Camp Rock telefilms:
- The first film is completely diegetic in its music, with the characters as young musicians at a music summer camp who sing, play instruments, and write the songs that are sung.
- In the second film, this gets Zigzagged. While most of the songs are still the result of in-universe performances, there are also songs added that just involve the characters breaking out into song and forgetting it afterwards, turning this film into a blend of diegetic and non-diegetic music.
- Eurovision Song Contest: The Story of Fire Saga: The film centers around a song contest, and all the songs are performed as part of the contest. The one exception, "Volcano Man," is an Imagine Spot where Lars and Sigrit imagine themselves in a music video while practicing their singing.
- In The Irony of Fate, both Zhenya and Nadya enjoy singing and playing the guitar, and are often asked to do so. It even includes a moment of Hypocritical Humor, when Nadya's friends ask her to sing and Zhenya refuses to listen, saying he doesn't like amateur performances.
- Once is about two musicians performing songs for each other and eventually recording an album together.
- The plot of Phantom of the Paradise is centered on a songwriter's operatic adaptation of Faust, the evil music mogul Swann stealing it and framing him for a crime and the opening of Swan's new concert hall "The Paradise". Every song in the film is presented as an In-Universe performance, whether it's a concert, audition or the live-showing of the eponymous opera.
- Rags, being a musical-themed Cinderella story involving the aspiring musician Charlie, pop star Kadee Worth, and Charlie's equally-aspiring but less-talented stepbrothers, it's only natural that the characters would be putting on in-universe performances. Thus, all of the music is from Charlie and Kadee's shows and rehearsals, his stepbrother's own musical act, or in the case of one song, being played in-universe as music for a masquerade party.
- Several songs in Sorcerers are justified in-universe. "The Centaurs" is the song of a band that is one of the candidates to sing at the New Year party. Nina sings "Three White Horses" and "Snowflake Song" as part of her masquerade as lead vocalist of the band that does get invited for the party. "The Serenade" is when the musical instruments' factory staff sing a song to the telephone operator to persuade her not to terminate the call.
- Nickelodeon's telefilm Spectacular! makes it a point to promote itself as a diegetic musical; the songs are performed as rehearsal scenes, performances on stage, etc. The big love ballad between the two main characters actually takes place at an arcade where they and the other characters are playing a Rock Band-type game and the two take up the vocals for a known song.
- A Star Is Born (2018) has a original soundtrack, and all the songs are performances in front of live crowds or for television.
- The Wedding Singer: As the title suggests, Robbie is a wedding singer and performs most of the songs in his professional capacity. The one major song he sings while not working is when he sings to Julia on the airplane, accompanying himself on the guitar.
- Since Voyage of the Rock Aliens prominently features two different bands, most of the songs are diegetic, although it's unclear if the backup dancers are too.
- In the Buffy the Vampire Slayer musical episode "Once More With Feeling", a demon's influence on the characters forces them to express their innermost feelings in song.
- Musical dramedy Katy Keene has both diegetic musical numbers and the traditional "break out into song" musical numbers; the diegetic numbers happen more often and are usually performances by Josie or Jorge at the gay bar Molly's Crisis. One of the fan favorite performances, a rendition of the cast singing Christina Aguilera's "Dirrty", was completely diegetic, with Pepper actually starting up the music on a vinyl player.
- The songs in Kids Incorporated are all performed on stage at THE PL*ACE, where the titular group hangs out.
- Psych: "The Musical" features Shawn and Gus searching for a supposedly insane playwright... aided by frenemy Mr. Yang. In order to keep Yang happy so that she'll help with the investigation, Shawn, Gus, Jules, and Lassie all agree to sing musical numbers to entertain her.
- Played with on the musical episode of Scrubs. It's established In-Universe that the characters aren't actually singing, but they appear to be singing to the patient for medical reasons.
- Smash is an odd case in that it features characters performing in in-universe musicals, characters spontaneously bursting into "real-life" choreographed numbers, characters singing in neither context and "mind palace" choreographed numbers.
- Zoey's Extraordinary Playlist: Zoey sees people breaking into musical numbers, but it's established In-Universe that she's hallucinating and she's well aware of the fact that it's not real. In one episode, she starts breaking into song herself, and unfortunately for her it's very real.
- In Il viaggio a Reims by Gioacchino Rossini, the finale has all the characters stage an amateur concert in honor of King Charles X.
- The Phantom of the Opera is set in an opera house, so some of its musical numbers are snippets of performances from fictional operas, such as "Think of Me" and "The Point of No Return".
- Big City Greens: The show's second Musical Episode "Okay Karaoke" is this, as all the songs are performed as karaoke acts by the Greens.
- Phineas and Ferb plays with this. Many of the songs play out as though they're just characters breaking into random, unexplained musical numbers, but these musical numbers still occur in-universe and are just accepted as something that happens in Danville. One episode, "Rollercoaster: The Musical" takes this farther and has Phineas's daily project be to build another rollercoaster...but this time as a musical. Every character follows suit and many of them openly acknowledge having to do musical numbers, because that's just what they're doing that day. Many other examples involve characters putting on performances, knowingly breaking out into random song, and even paying background dancers to be there.
- Parodied in the Rocko's Modern Life episode "Zanzibar"; the whole town sings a whole song about recycling, and when Rocko asks how they came up with the song on the spot, the townspeople say that they didn't, they practice this song every week.