Ryan was born into a middle-class family in Sunland, Los Angeles, California. She is of French, Colombian, and Irish decent. Her parents are together, and she has three sisters.

Ryan has been singing since the age of seven, and it was around the age of 19 when she developed a passion for rock n' roll. She went to Verdugo Hills High School, where she was Prom Queen and head-cheerleader. She was a member of many school clubs, and played various sports such as track and surfing. "I did everything, people should really try and be a part of a lot of things. It keeps life fun and keeps you fit, too!" She also sang whenever possible at school events. She has been quoted as saying, "I fell in love with the raw emotions rock has to offer. Music is simply my life, I live through it."

Once Ryan knew what kind of music she wanted to sing, she began to do anything and everything to sing and get on stage. Still only a teenager, she worked for free as a waiter at clubs to sing on stage afterwards. Music quickly took over her life, and she decided to put college on hold in order to pursue her dream of becoming a rock-star. She listened to all kinds of rock singers, from legends like Aerosmith and Led Zeppelin to female artists like Pat Benetar and Janis Joplin. Upon realizing that today there are no female rock-stars, she decided that she wanted to fill that void.

Ryan appeared on the first season of American Idol displaying a unique, throaty, and smooth voice while wearing her own fashion-designs on stage. Ryan sang an unusual song, "The Frim Fram Sauce," in the first Group of Ten vying for spots in the Top Ten. She was voted the second spot from that group to move into the Top Ten. Next week, Ryan was the first to perform on American Idol's first live show. She sang "If You Really Love Me" by Stevie Wonder, and received praise from the judges. "Pure star performance, loved it." (Simon Cowell.) The famed 'Jaded Journalist,' an online reporter from American Idol's website said, "I want to see Kelly and Ryan battle it out in the final two!" She faltered when she sang, "You Really Got Me," a Kinks classic and was panned by the judges. Simon Cowell called it "dreadful". However, the following week Ryan sang "Last Dance" by Donna Summers and received praise from the judges.

When eliminated in 7th place, Starr received encouraging words from the judges. "You're a star, it's in your name, you'll make it." - Randy Jackson. "I don't understand you should not be leaving us tonight. Don't worry things are going to turn out great for you." - Paula Abdul. "You know Ryan, I think you're different from all the rest, and I think you can get what you want. Give me a call anytime; because you're about to become a star, I'll give you any help you need." - Simon Cowell.

Ryan returned with the rest of the finalists during the show's finale and sang, "These Boots Are Made For Walkin'", and went on a nation-wide 32 city tour with the other finalists.

RCA, in partnership with American Idol, signed Ryan along with fellow Season One contestants Kelly Clarkson, Justin Guarini, Nikki McKibbin, Christina Christian, and Tamyra Gray (with J Records).