On the Billboard Hot Country Songs chart dated for the week of September 2, 2007, "Our Song" debuted at No. 55. The song reached No. 1 on the chart week of December 22, 2007, when it moved up from the No. 6 position. The five-notch jump to No. 1 was the biggest on the Hot Country Songs chart since January 1998, when Tim McGraw's "Just to See You Smile" also moved up from #6 to Number One.
With six weeks at No. 1, "Our Song" forged a four-way tie for the second-longest running No. 1 by a female artist in the history of the Billboard Hot Country Songs charts. Other songs also spending six weeks atop the chart are "It Wasn't God Who Made Honky Tonk Angels" by Kitty Wells (in August 1952), "Breathe" by Faith Hill (January 2000) and "Jesus, Take the Wheel" by Carrie Underwood (February 2006). Only Connie Smith's "Once a Day" had a longer reign, accomplishing its feat in January 1965.
"Our Song" eventually became a crossover hit, becoming Swift's first Top 20 entry on the Billboard Hot 100. The song eventually peaked at No. 16.