 "I Want You" is a pop ballad based on music of the Motown era. It incorporates doo-wop, R & B and hip-hop into its production, providing an "equally keen senses of retroism and hip-hop currency." Its instrumentation consists of guitar, piano, violins, and synthesized drums. It has a slow tempo of 72 beats per minute, with Jackson's vocals ranging from G3 to C5. It contains a brief sample from B. T. Express' 1976 version of The Carpenters'1970 song "(They Long to Be) Close to You", written by Burt Bacharach and Hal David. Jackson described the song as having a "throwback" feel, considered a departure from her other works. Michael Paletta of Billboard described its "opening drum downbeat" accompanied by "swirling string crescendos," considered "the perfect backdrop for Jackson's breathy vocals." It was analyzed to have a "chimes-studded texture" and strings backed by drums, also having "a triangle thrown in there for good measure." Its lyrics focus on longing for an estranged lover and feeling emotionally distraught when apart. Jackson pleads for their affection during its chorus, telling them to "Have your way with me." Tareck Ghoneim of Contactmusic.com stated "The lyrics are simple. She just wants her man and she ’ s telling it straight," while Plugged In observed it to convey Jackson's "insatiable" desire for intimacy in a "vulnerable and lovesick" manner.
