The song was partly recorded at Rockfield Studios in Wales.
Besides using his grand piano as usual, Mercury overdubbed the song with an upright piano to give the track a vaudeville sound.
"Killer Queen" was Queen's breakthrough hit, reaching number two in the United Kingdom and number twelve in the United States.
The song was regularly performed between 1974 and 1981 as part of a medley.
The song won Mercury his first Ivor Novello Award.
The song's first verse quotes a phrase falsely attributed to Marie Antoinette: " 'Let them eat cake,' she says, Just like Marie Antoinette.
"Killer Queen" retained the essence of Queen's trademark sound, particularly in its meticulous vocal harmonies.
Rock historian Paul Fowles wrote that "Killer Queen", with its "sleazy Parisian imagery", allowed "free rein" to Mercury's "unique brand of rock theater".
American pop singer Katy Perry cites "Killer Queen" as an important influence on her. She said: "Queen's track 'Killer Queen' made me discover music and helped me come into my own at the age of 15. The way Freddie Mercury delivered his lyrics just made me feel like a confident woman."
United Kingdom (BPI) Silver certification with 250,000 sales.