The film opens with preparations being made for the historic Live Aid concert in 1985. As the stage is set, running to the front is the legendary rock star, Freddie Mercury (Rami Malek).
In a flashback to 1970, Freddie is seen working as a baggage handler at London's Heathrow Airport. He lives with his parents Jer (Meneka Das) and Bomi (Ace Bhatti), and sister Kashmira (Priya Blackburn), and lives as Farrokh Bulsara, but he prefers to be called Freddie.
Freddie attends a show at a club to see a band called 'Smile' perform. After the show, members Brian May (Gwilym Lee) and Roger Taylor (Ben Hardy) are told by their front man Tim Staffell (Jack Roth) tells them that he wants out of the band to pursue bigger opportunities. As he looks for the band, Freddie meets Mary Austin (Lucy Boynton) and compliments her scarf, which she says is from the store she works at. Freddie then approaches Brian and Roger after the show to compliment their performance and offer to be their new singer. They seem unconvinced at first, especially with Freddie's large teeth, but Freddie sings for a moment to show off what he can do.
Freddie joins Brian and Roger, along with their new bassist John Deacon, or "Deaky" (Joseph Mazzello). Someone in the audience comments on Tim's absence and replacement with a "paki". After a bit of an awkward start, Freddie shows off his talent, despite singing some of the lyrics a bit incorrectly.
A year later, the band is getting steady work performing gigs across England, and Freddie has been dating Mary. After their van breaks down, Freddie proposes that they sell it to record their first album, and they start to go by the band name 'Queen'.
Mary and the guys have lunch at Freddie's home, joined by Mary's deaf father. Jer tells the guests how their family were originally from Zanzibar until they were chased out of there. Freddie then answers the phone and tells the guys that a music manager named John Reid (Aiden Gillen), who works with Elton John, has listened to their demo and wants to meet and manage Queen, to the excitement of the other guys.
The band meets with Reid, who introduces them to Paul Prenter (Allen Leech), another manager. Reid gets the band to go on a popular BBC show to perform "Killer Queen", but they initially clash with the show's producers for wanting them to perform the way the network wants them to (mainly lip-syncing the song).
At home, Freddie proposes to Mary, who accepts. The other guys come in to tell Freddie that Reid has booked the band a tour of America. The band embarks on their U.S. tour to ecstatic sold-out concerts. They also hire lawyer Jim Beach (Tom Hollander), or "Miami" as Freddie prefers. The band, plus Reid and Beach, meet with EMI's record producer Ray Foster (Mike Myers) to make their next album. Freddie proposes something similar to an experience of going to the opera, and so he wants to call it "A Night at the Opera."
The band stays together as they work toward their next big hit. While trying to write new songs, Paul approaches Freddie and kisses him. Although he doesn't try to resist, Freddie tries to make it seem like he doesn't feel somewhat similarly toward Paul, who claims he knows Freddie as well as he knows himself.
Despite some disagreements, the band comes to create "Bohemian Rhapsody". They play it for Foster, who thinks it's too long at six minutes and is comprised of nonsense words. He would rather use Roger's "I'm in Love With My Car" or "You're My Best Friend" to be the main single on the album over "Bohemian Rhapsody", since he thinks those songs would play better with a young demographic while no radio station will want to play a long song. Queen decide to turn their backs on Foster and EMI. Freddie takes "Bohemian Rhapsody" to DJ Kenny Everett (Dickie Beau) to play it for the very first time to the public. It receives mixed to outright scathing reviews, but it becomes one of the band's biggest hits that they play at venues all over the world.
After the world tour, Freddie meets with Mary, whom he had been distancing himself from on the road. He comes out to Mary as bisexual, but she tells him she thinks he's gay. She starts to cry as she is tired of all of Freddie's excuses, and she breaks up with him.
Freddie cuts his hair short and sports his now famous mustache. He owns his own home next to Mary, but he appears to be lonely. He calls Paul to arrange a party and invite a bunch of strangers. Freddie invites the band, but he starts to behave all crass and rudely toward them, prompting them to leave. After the party, Freddie gropes a waiter, Jim Hutton (Aaron McCusker). Although he offends Jim, Freddie apologizes and invites him to stay. The two chat and share a kiss before Jim leaves, but he invites Freddie to find him after he's found himself.
Brian comes up with a new song that he thinks will encourage the audience to perform along with the band - "We Will Rock You". Sure enough, it becomes another smash hit. After one of Queen's performances, Paul approaches Reid and suggests that they try and get Freddie to go solo. Meanwhile, Freddie finds Mary with her new boyfriend David (Max Bennett). On the way home from the show, Reid offers the solo deal to Freddie, but it only enrages him to even think about leaving the band, and Freddie fires Reid.
Freddie's behavior gets worse as he shows up to rehearsals late and almost fights with Roger. However, for all that rancor, the band remains productive: they settle their arguments as Deaky creates a catchy new bass line that inspires a new hit, "Another One Bites The Dust".
The band goes to a press conference where reporters hound Freddie with questions about his sex life and orientation, due to ongoing rumors that he has been engaging in gay orgies. He appears too overwhelmed and dazed to properly answer questions when he is not being rude to the reporters.
Queen then does a video for "I Want To Break Free", which gets banned by MTV for featuring the group in drag. Later, Freddie tries to get in touch with Jim, but finds that there are a large number of Jim Huttons in the phone book.
Freddie later confesses to the others that he signed a $4 million solo contract with CBS Records, which deeply upsets the others. As Freddie leaves, Brian tells Freddie that he needs them more than he realizes.
Freddie moves to Munich, West Germany to record his solo album, "Mr. Bad Guy". One night, he is visited by Mary, who says she is pregnant. She tries to convince Freddie to rejoin the band as they have been offered a spot to perform at the Live Aid benefit concert for Africa. Mary leaves, but Freddie confronts Paul about not telling him about Live Aid. He breaks up with Paul and demands that he never see him again. In retaliation, Paul goes on TV to discuss his sexual relations with Freddie.
Freddie gets in touch with Beach and manages to get the others together to discuss joining Live Aid. He apologizes to the guys for his behavior and abandoning them. Beach tells them that the lineup is fully booked, but he talks to Bob Geldof and convinces him to let them perform, and they all agree under the condition that anything they come up with be credited to Queen as a whole and not to any individual one of them.
The band starts to practice for the show, but Freddie falls ill. He sees a doctor and gets the diagnosis that he tested positive for AIDS. Freddie tells the band about it, but he doesn't want them to feel bad for him as long as they can continue to perform together as friends. They all then get together for a group hug.
The day of Live Aid has arrived. Freddie finds Jim and invites him to come see the show. He visits his family and shows them love before heading to the performance. Bomi decides he will want to watch the show on TV with his family. While at the show, Mary and David arrive, and Jim joins them backstage to watch the show.
It is now Queen's turn to perform. They start with "Bohemian Rhapsody", where Freddie blows a kiss to the camera for his family. The next song is "Radio Ga Ga", followed by "Hammer To Fall", and finally "We Are The Champions", where people watching everywhere sing along to. Numerous calls for pledges come in, bringing in over £1 million, and Queen's performance is so epic that it drives many viewers to tears. After the performance, the guys walk away like true champions.
The final text states that Freddie Mercury died in 1991 from AIDS-related pneumonia at age 45. He was in a relationship with Jim Hutton for the rest of his life, and he remained good friends with Mary Austin until his death. Jim Beach and the surviving members of Queen joined to create the Mercury Phoenix Trust to help fight AIDS worldwide.