"If Your Girl Only Knew" debuted on the US
Billboard Hot 100 at number 34 during the week of August 31, 1996. The song reached its peak at number 11 eight weeks later on the chart dated October 19. On the
Hot R&B Singles chart, the song debuted at number 12 the week of August 31. On September 28, it reached its peak at number one, remaining atop the chart for two consecutive weeks. According to Datu Faison from
Billboard, "Key factors leading to Aaliyah's big 5–1 leap include a 20% unit increase at R&B core stores, which pushes an identical 5–1 jump on hot R&B singles sales. Audience impressions increase another 9%, moving the record 9–7 on Hot R&B airplay". The song also peaked at number six on the
Top 40/Rhytym-Crossover chart during the week of November 2. Towards the end of 1996, it was reported by
Billboard that the single had sold over 600,000 copies in the United States. Internationally, "If Your Girl Only Knew" originally peaked at number 21 on the
UK Singles Chart on August 24, 1996. In 1997, the single was re-released as a
double A-side single with "
One in a Million" and reached a new peak position at number 15 on May 24, 1997. and at number four on the
UK R&B Chart on August 25, 1996. According to the
Official Charts Company (OCC), the "If Your Girl Only Knew" standalone single is Aaliyah's tenth best-selling single in the United Kingdom, while the double single is her sixth. "If Your Girl Only Knew" also peaked at number 20 in New Zealand on October 20, 1996. Following its 2021 digital release, "If Your Girl Only Knew" debuted at number 15 on the US
Digital Song Sales chart for the week of September 4, 2021. ==Music video==