The cable network previously announced rocker Steven Tyler and music producer Randy Jackson would be back on the judges' panel for the upcoming 11th season. However, Lopez' participation wasn't announced until Wednesday.
The singing competition series' creator and executive producer Simon Fuller confirmed the casting news to The Hollywood Reporter.
"Having both Jennifer and Steven return to 'Idol' in 2012 alongside Randy is such a positive reflection on what was a wonderful and hugely successful season last year, and everyone is delighted," Fuller said in a statement issued to the entertainment industry trade newspaper.
"I am very pleased to have our panel of judges back for the 11th season of 'American Idol,'" added executive producer Cecile Frot-Coutaz. "Their chemistry and ability to select amazing talent made last season one of our most successful yet, and we look forward to going on another exciting ride."
Lopez and Tyler joined the "Idol" cast in Season 10.