The album's title is an homage to MacFarlane's best-known voice-acting role as Hayley Smith in her brother's series American Dad!.

Shortly after sending her demo tape, MacFarlane was signed to Concord Records, where she would soon begin work on Hayley Sings.

When I was growing up, my dad introduced me to groups like Simon and Garfunkel and The Beatles and Crosby, Stills, and Nash.

In his AllMusic review, Mark Deming, while praising MacFarlane's vocal ability (in particular her simple renditions of "Since You Asked" and "Loneliness"), described most of the selections as being sung with a melodrama which is "embarrassing and overbearing," as well as noting that if the album was truly Hayley Smith singing, it would either "be dominated either by Ani DiFranco tunes, hipster indie rock in the manner of the Arcade Fire, noodle-dance-friendly jam band material, or some combination thereof."

Bill Bliss for Edge, while again praising MacFarlane's voice as having "all the qualities associated with a fine chanteuse, a stylish big band vocalist or theatre-trained ingénue," criticized the album's fifteen-track length, as "there is hardly time to zero in on one aspect of her voice before the next selection veers off into another zone of musical territory...Sliced down to seven or eight tracks, 'Hayley Sings' would have kept the animation of Rachael MacFarlane’s true talent intact."