Fantasia sang "I Believe" on the third season finale of American Idol as her last performance within the competition. Diana DeGarmo, the runner up of American Idol Season 3, sang the song first, also on the finale, for her first performance of the night. The judges unanimously acclaimed Fantasia the winner of season 3, a prediction that came true when she was crowned American Idol the following evening. An ecstatic and tearful Fantasia performed her new single "I Believe" minutes after the announcement. DeGarmo's performance was also well received by the judges.
The song was an instant success for Fantasia when it was released on June 22, 2004. It performed well on the radio and sales charts of the United States and Canada debuting at number one in both nations. This made Fantasia the first artist in the history of the Billboard Hot 100 to debut at number one with a first record. "I Believe" is also the winner of three Billboard Awards. "I Believe" is noted for its inspirational lyrics.
When the song was released it debuted on the Billboard Hot 100 at number one for one week and dropped out of the US Top 40 after four weeks. In its debut week the single shattered the first week sales record for any single in 2004 in the US, and was certified double platinum by the CRIA in Canada, selling more than 80,000 units. It has sold 527,000 copies in the United States, making it one of the most successful singles of 2004. "I Believe" was number one on the US single sales chart for eleven consecutive weeks and ten weeks in Canada, giving it the longest stay at number one on the chart by any Idol contestant. "I Believe" also spent six consecutive weeks at number one on the US R&B Single Sales chart. "I Believe" hit number one on more music charts than any other Idol contestant's debut single so far. On the US Billboard Hot 100 chart, it still remains the only No. 1 single to not chart on the Year-End Chart that did not peak near the Billboard chart year cut off.