The ninth season of American Idol premiered on Fox on Tuesday, January 12, 2010, and concluded on Wednesday, May 26, 2010. Simon Cowell, Kara DioGuardi, and Randy Jackson returned as judges and were joined by Ellen DeGeneres, who was brought on as a replacement for Paula Abdul after a series of guest judges filled in for the auditions. Idol Gives Back returned on April 21, 2010. The top 24 semifinal format used in the fourth through seventh seasons also returned this season. Cowell, DioGuardi, and DeGeneres all left the show after this season, although only Cowell's departure was announced in advance.

Lee DeWyze, a folk rocker from Mount Prospect, Illinois, won the competition, beating out fellow folk rocker Crystal Bowersox, who was the runner-up. Multiple contestants from this season were signed to record deals including DeWyze, Bowersox, Casey James, Michael Lynche, and Siobhan Magnus. Several contestants who did not even make it to the semifinals eventually had a breakthrough in the music industry, including Tori Kelly, Lauren Daigle, and Tasha Layton.

Changes from previous seasons Paula Abdul did not return to the judges panel, having announced in the beginning of August 2009 that she was leaving the show due to unresolved contract negotiations. Victoria Beckham, Mary J. Blige, Shania Twain, Katy Perry, Avril Lavigne, Joe Jonas, Neil Patrick Harris, and Kristin Chenoweth were brought on as guest judges during the auditions.

After making the decision to utilize guest judges in Abdul's absence, Fox chairman Peter Rice said that they would find a permanent fourth judge before the season premiere in January 2010. Ellen DeGeneres confirmed on September 9, 2009, that she would be joining the show as the new permanent fourth judge for the rounds held at CBS Television City for Hollywood Week and thereafter.

Additionally, Simon Cowell announced shortly before the ninth season began that it would be his last season on American Idol. Cowell left the show to begin preparations for an American version of his singing competition The X Factor. DeGeneres announced on July 29, 2010, that she would not return to the judges panel because it was not the "right fit" for her. Kara DioGuardi also announced on September 3, 2010, that she would not return as a judge for the tenth season.

Regional auditions Auditions began on June 14, 2009, less than a month after the previous season's finale. During this stage, a series of guest judges filled in on the judging panel. Auditions were held in the following cities.

+American Idol (season 9) – regional auditions City Preliminary date Preliminary venue Filming date(s) Filming venue Guest judge Golden tickets Boston, Massachusetts June 14, 2009 Gillette Stadium August 13–14, 2009 60 State Street Victoria Beckham 32 Atlanta, Georgia June 18, 2009 Georgia Dome August 16–17, 2009 W Hotel Atlanta Midtown Mary J. Blige 25 Chicago, Illinois June 22, 2009 United Center August 31 – September 1, 2009 Hyatt Regency Chicago Shania Twain 13Dallas, TexasJune 26, 2009Cowboys StadiumAugust 24, 2009W Hotel Dallas Victory Joe Jonas31 August 25, 2009 Neil Patrick HarrisLos Angeles, CaliforniaJune 30, 2009Rose Bowl Stadium September 3, 2009Marina del Rey Marriott Katy Perry23 September 4, 2009 Avril Lavigne Orlando, Florida July 9, 2009 Amway Arena August 28–29, 2009 Rosen Shingle Creek Resort Kristin Chenoweth 31 Denver, Colorado July 14, 2009 Invesco Field August 7–8, 2009 Grand HyattAmerican Idol in Denver – Photo Gallery Victoria Beckham 26 Total number of tickets to Hollywood 181

Hollywood week Held at the Kodak Theatre for the second straight year, the first day of Hollywood Week featured the 181 contestants from the auditions roundGolden Ticket Interviews American Idol singing solo with the option of playing an instrument. Ellen DeGeneres made her first appearance as a judge at this time. 96 contestants advanced. The next round required the contestants to split into groups and perform. 71 advanced to the final round of Hollywood requiring a solo performance. 46 made it to the final round, where the judges spoke to the contestants one-by-one to tell them whether they had made the final 24.

Semifinals The semifinal format used during the fourth through seventh seasons was revived for this season. Starting with twelve women and twelve men, the women and men performed weekly on separate shows, each performing a Billboard Hot 100 song, and on the results show, the bottom two contestants from each group were eliminated from the competition. The semifinals took place over three weeks, meaning that six men and six women were eliminated, leaving the other six men and six women to form the top 12. The women performed on the first night, and the males the next night. However, the men and women switched on March 2 and March 3, because Crystal Bowersox had been hospitalized due to complications from diabetes.Crystal Bowersox could be a game-time decision tonight USA Today, March 3, 2010

Color key:

Top 24 Contestants are listed in the order they performed. +Top 24 - Female contestants (February 24) Contestant Song Result Paige Miles "All Right Now" Safe Ashley Rodriguez "Happy" Eliminated Janell Wheeler "What About Love" Eliminated Lilly Scott "Fixing a Hole" Safe Katelyn Epperly "Oh! Darling" Safe Haeley Vaughn "I Want to Hold Your Hand" Safe Lacey Brown "Landslide" Safe Michelle Delamor "Fallin'" Safe Didi Benami "The Way I Am" Safe Siobhan Magnus "Wicked Game" Safe Crystal Bowersox "Hand in My Pocket" Safe Katie Stevens "Feeling Good" Safe+Top 24 - Male contestants (February 25) Contestant Song Result Todrick Hall "Since U Been Gone" Safe Aaron Kelly "Here Comes Goodbye" Safe Jermaine Sellers "Get Here" Safe Tim Urban "Apologize" Safe Joe Muñoz "You and I Both" Eliminated Tyler Grady "American Woman" Eliminated Lee DeWyze "Chasing Cars" Safe John Park "God Bless the Child" Safe Michael Lynche "This Love" Safe Alex Lambert "Wonderful World" Safe Casey James "Heaven" Safe Andrew Garcia "Sugar, We're Goin Down" Safe + Non-competition performance Performers Song Top 24"American Boy" Allison Iraheta "Scars" Kris Allen "Let It Be"

Top 20 Contestants are listed in the order they performed. +Top 20 - Male contestants (March 2) Contestant Song Result Michael Lynche "It's a Man's Man's Man's World" Safe John Park "Gravity"Eliminated Casey James "I Don't Want to Be" Safe Alex Lambert "Everybody Knows" Safe Todrick Hall "What's Love Got to Do with It" Safe Jermaine Sellers "What's Going On"Eliminated Andrew Garcia "You Give Me Something" Safe Aaron Kelly "My Girl" Safe Tim Urban "Come On Get Higher" Safe Lee DeWyze "Lips of an Angel" Safe+Top 20 - Female contestants (March 3) Contestant Song Result Crystal Bowersox "Long As I Can See the Light" Safe Haeley Vaughn "The Climb" Eliminated Lacey Brown "Kiss Me" Safe Katie Stevens "Put Your Records On" Safe Didi Benami "Lean on Me" Safe Michelle Delamor "With Arms Wide Open" Eliminated Lilly Scott "A Change Is Gonna Come" Safe Katelyn Epperly "The Scientist" Safe Paige Miles "Walk Away" Safe Siobhan Magnus "Think" Safe + Non-competition performance Performers Song Top 20"I Gotta Feeling" Danny Gokey "My Best Days Are Ahead of Me"

Top 16 Contestants are listed in the order they performed. +Top 16 - Female contestants (March 9) Contestant Song Result Katie Stevens "Breakaway" Safe Siobhan Magnus "The House of the Rising Sun" Safe Lacey Brown "The Story" Safe Katelyn Epperly "I Feel the Earth Move" Eliminated Didi Benami "Rhiannon" Safe Paige Miles "Smile" Safe Crystal Bowersox "Give Me One Reason" Safe Lilly Scott "I Fall to Pieces" Eliminated+Top 16 - Male contestants (March 10) Contestant Song Result Lee DeWyze "Fireflies" Safe Alex Lambert "Trouble" Eliminated Tim Urban "Hallelujah" Safe Andrew Garcia "Genie in a Bottle" Safe Casey James "You'll Think of Me" Safe Aaron Kelly "I'm Already There" Safe Todrick Hall "Somebody to Love" Eliminated Michael Lynche "This Woman's Work" Safe + Non-competition performance Performers Song Top 16"Haven't Met You Yet" Matt Giraud and Scott MacIntyre "Tell Her About It"

Top 12 finalists

Lee DeWyze (born April 2, 1986, in Mount Prospect, Illinois; 23 years old at the start of the show) was from Mount Prospect, and auditioned in Chicago with Bill Withers' "Ain't No Sunshine." He performed The Fray's "You Found Me" in Hollywood. Crystal Bowersox (born August 4, 1985, in Elliston, Ohio; 24 years old at the start of the show) was from Elliston, and auditioned in Chicago with Erma Franklin's "Piece of My Heart." Her Hollywood performance of Aretha Franklin's "(You Make Me Feel Like) A Natural Woman" impressed the judges and fellow contestants alike. She was diagnosed with Type 1 diabetes when she was six, and while on the show, she suffered diabetic complications and was hospitalized, which resulted in the top 20 performance nights for the male and female contestants to switched. Casey James (born May 31, 1982, in Princeton, Texas; 27 years old at the start of the show) was from Fort Worth, Texas, and auditioned in Denver with John Mayer's "Slow Dancing in a Burning Room." Michael Lynche (born May 31, 1983; 26 years old at the start of the show) was from St. Petersburg, Florida, and auditioned in Orlando with Todd Duncan's "Unchained Melody." His daughter was born during the Hollywood round, and the unfolding drama of his wife's labor was heavily featured while he performed John Mayer's "Waiting on the World to Change." Aaron Kelly (born April 2, 1993, in Davenport, Florida; 16 years old at the start of the show) was from Sonestown, Pennsylvania, and auditioned in Orlando with Miley Cyrus's "The Climb." He performed Sarah McLachlan's "Angel" in Hollywood, where he forgot his words. Siobhan Magnus (born March 15, 1990, in Barnstable, Massachusetts; 19 years old at the start of the show) was from Cape Cod, Massachusetts,Although the American Idol website lists Siobhan Magnus' hometown as Cape Cod, Massachusetts. Siobhan is specifically from Marstons Mills, Massachusetts, a village in the town of Barnstable, Massachusetts within Cape Cod, Massachusetts. and auditioned in Boston with Queen's "Love of My Life." She performed Stevie Wonder's "Living for the City" in Hollywood. Tim Urban (born May 1, 1989, in Tacoma, Washington; 20 years old at the start of the show) was from Duncanville, Texas, and auditioned in Dallas with Matt Nathanson's "Bulletproof Week." He performed David Cook's "Come Back To Me" in Hollywood. He did not initially qualify for the semifinals, but was chosen as a replacement when Chris Golightly was disqualified from the competition. Katie Stevens (born December 8, 1992, in Southbury, Connecticut; 17 years old at the start of the show) was from Middlebury, Connecticut, and auditioned in Boston with Glenn Miller's "At Last." She performed Jean DuShon's "For Once in My Life" in Hollywood, where Kara DioGuardi considered her a potential winner. Andrew Garcia (born October 8, 1985, in Moreno Valley, California; 24 years old at the start of the show) auditioned in Los Angeles with Maroon 5's "Sunday Morning." He impressed the judges with his performance of Paula Abdul's "Straight Up" in Hollywood. Didi Benami (born October 25, 1986, in New York City, New York; 23 years old at the start of the show) was from Knoxville, Tennessee, and auditioned in Los Angeles with The Beatles' "Hey Jude." She performed Katharine McPhee's "Terrified"–penned by Kara DioGuardi–in Hollywood. Paige Miles (born September 26, 1985; 24 years old at the start of the show) was from Naples, Florida, and auditioned in Dallas. She performed Stevie Wonder's "Living for the City" in Hollywood.