American Idol (season 8) Guest performances Guest performances

| Week | Performers | Hot_100_Reaction | Hot_Digital_Songs_Reaction | Notes |
|---|---|---|---|---|
| Top 10 | Ruben Studdard | did not debut | N/A | pre-recorded |
| Top 10 | Smokey Robinson Joss Stone | did not debut | N/A | live performance |
| Top 10 | Stevie Wonder | ineligible to re-enter | N/A | live performance |
| Top 9 | David Cook | 63 (debut) | 40 (39,430 +498%) | pre-recorded |
| Top 9 | Lady Gaga | 2 (+1) | 2 (228,799 +11%) | live performance |
| Top 8 | Frankie Avalon | N/A | N/A | live performance |
| Top 8 | Flo Rida Wynter Gordon | 3 (=) | 4 (179,913 +9%) | live performance |
| Top 8 | Kellie Pickler | 50 (+53) | 34 (46,825 +257%) | live performance |
| Top 7 (week 1) | Jennifer Hudson | 63 (+23) | 86 (19,112 +172%) | live performance |
| Top 7 (week 1) | Miley Cyrus | 4 (+4) | 2 (189,566 +0%) | pre-recorded |