In fact, she was one of the first semi-finalists to make it to the final 12. A native of Sherman Oaks, California, McPhee began singing at age two. Her mother, Patricia McPhee, is an established singer in her own right, performing and recording as Peisha McPhee. She helped Katharine develop as a vocalist and gave her more formal training than many American Idol hopefuls receive. Though McPhee sang and acted throughout her childhood and high school years, she began taking singing more seriously in college, attending Boston Conservatory as a musical theater major. After three semesters, however, she left for Los Angeles to audition for film and television work. McPhee scored roles in the film Crazy, a musical about Hank Garland, and an MTV series, You Are Here, which didn't make it to the air. She also appeared in productions of Annie Get Your Gun and The Ghost and Mrs. Muir before auditioning for American Idol in 2005.

Once McPhee made the final 12, her performances of songs such as "Someone to Watch Over Me," "Come Rain or Come Shine," and "Black Horse and the Cherry Tree" made her one of the favorites of American Idol judges and viewers. After the American Idol season ended, McPhee was signed by show creator Simon Fuller's 19 Recordings Limited label and released her first single, Somewhere Over the Rainbow/My Destiny; it became the second best-selling single of 2006. That summer, after bouts with bronchitis and laryngitis, she joined the rest of the finalists and Hicks on the American Idols LIVE! tour and also toured with Andrea Bocelli, who appeared on American Idol as a guest judge. McPhee began recording her self-titled debut album in the fall, working with collaborators such as Timbaland's production partner, Nate "Danja Hand" Hills, Chad Hugo of the Neptunes, and songwriter Kara DioGuardi. "Over It," which was written by the songwriting team of Billy Steinberg, Josh Alexander, and Ruth-Anne Cunningham, arrived a few weeks before Katharine McPhee was released in early 2007. In 2010, McPhee returned with the holiday-themed album Christmas Is a Time...To Say I Love You.

McPhee turned her attention to acting in 2011, landing a pivotal role on NBC's Smash. The music-based soap ran for two seasons and, additionally, McPhee appeared in the 2011 indie films You May Not Kiss the Bride and Peace, Love & Misunderstanding. In 2014, she landed the lead role in the CBS drama Scorpion. As the show was leading up to its second season in 2015, McPhee returned to music, releasing the single "Lick My Lips" that April. It was a teaser for a full-length record called Hysteria, which was her first pop album in five years. ~ Heather Phares