Mikael Wood of Billboard compared "Who Owns My Heart" to 2010 singles released by The Black Eyed Peas. "It’s commerce that owns your heart, Miley, and it always has been", he wrote. He said the chorus invites the answer: "probably that creepy bloke from the Disney Channel who went on about violating your godliness." Evan Sawdey of PopMatters also found an alternate answer to the song's chorus. Alexis Petridis of the United Kingdom magazine The Guardian felt the song was a gamely attempt at Lady Gaga. Tanner Stransky of Entertainment Weekly stated, "This song is a pulsy, possibly club-ready jam that deserves single status." Heather Phares of Allmusic used "Who Owns My Heart" as an example of, according to her, a recurring problem on Can't Be Tamed: "too often, Cyrus equates grown-up with joyless". The song's refrains proceed to question, "Who owns my heart? Is it love or is it art?" Verses and the bridge describe the setting using comparisons to numerous things, including tsunamis and rodeos. Lyrically, "Who Owns My Heart" speaks of the thrill of meeting a potential love interest on the dance floor. Keyboard riffs also drive the song's instrumentation. "Who Owns My Heart" is heavy in rubbery and bubbling disco synths.
It follows the chord progression A5–F5–D5–E5. It is written in the key of A minor and Cyrus' vocals span two octaves, from G3 to C5. The song is set in common time and has a driving dance tempo of 136 beats per minute. It is an uptempo and predominantly club-oriented number that has Techno influences, as well as Eurodance music qualities but in a darker tone, and is inspired by 1980s music. "Who Owns My Heart" is a dance-pop and electropop song with a length of three minutes and 35 seconds. She stated, "If you're out, dancing at a club, the way the whole vibe is Do you actually like the person you're dancing with or is just the whole ambiance of what's going on?"
Cyrus depicted the club scene to be very sexy, which she thought was primarily composed by the music playing and intense lighting, and thought that it might trigger fake emotions with the person one is dancing with. "Who Owns My Heart" was written about the feelings a club's environment can lead one to believe. Cyrus described it as a "total dance track" with a cool concept. The song was written by Cyrus in collaboration with Antonina Armato, Tim James, and Devrim Karaoglu.