Duff confirmed that she had collaborated with a rapper called Prophet on a previously unheard song on the Dignity tour's set list, "Reach Out" in September 2007. In an interview with remix producer Joe Bermudez in November 2007, she said that Dignity would be re-released in a CDVU+ edition featuring remixes of the original songs alongside two new tracks: "Reach Out" and "Holiday". Duff said she hoped to write a third new song for the re-release, and to have "Holiday" released as its first or second single; However, Hollywood Records scrapped the plans adding to their large list of cancelations, which in turn led Duff to make the decision to leave the label and develop Best of Hilary Duff to quickly end her contract, which had expected one more album.
Unlike Duff's first compilation album Most Wanted (2005), which was advertised as strictly a compilation, Best of was strictly advertised as a greatest hits, making it her first.
Best of Hilary Duff received mostly mixed reviews from critics. Allmusic gave the album a positive review stating that Best of Hilary Duff "is a flipside of her 2005's Most Wanted", which was "pitched squarely at bright, happy tweens". They also went on to say the album "is not a look back at the past but a blueprint for the future". Allmusic gave the album a 3.5/5 star rating. Commonsensemedia said that "parents need to know that Miss Duff has turned up the heat with sexually provocative lyrics that may be too hot to handle for younger fans. Hilary Duff isn't for tweens anymore. The hit single "Reach Out" features more aggressive sexual lyrics than on previous albums. While Dignity was OK for 11-year-olds, the Best Of compilation pushes the target age higher. The funky remixes and danceable electronic beats are fun and catchy, but the sexed-up lyrics and themes aren't intended for younger fans." Rachel Devitt of Rhapsody said the collection "is largely pleasant, nicely polished and, rather surprisingly, sleek and even a little edgy. Turns out Lizzie McGuire is a dancefloor diva, and even with that feathery little voice, she manages to work it on tracks like the dark "Stranger," saucy new tune "Reach Out" and a clubby remix of "Dignity."
Best of Hilary Duff debuted at number 125 on the US Billboard 200 chart, selling 5,500 copies in its first week of release in the US making it her least successful album to date. Many believe this was due to a lack of promotion from her record label at the time Hollywood Records. This is her first album not to receive any RIAA certifications. As of September 2012, the album has sold over 35,000 copies in the United States alone.
"Reach Out" was released as the only single from the album. The music video is directed by Philip Andelman and five official versions were released (though some have leaked first). The music video premiered on Duff's official MySpace on October 28, 2008.