"Look who's going to Hollywood! #IdolAuditions #kanyewest," Seacrest, who also produces Keeping Up with the Kardashians, wrote on Instagram.
"SURPRISE!" Kim, who wore a conservative black maxi dress with a jacket, captioned a photo on Instagram which featured West, Lopez and Connick all smiling on television monitors.
West, who dressed casually in a black T-shirt with jeans and a brown jacket, reportedly sang his 2005 hit "Gold Digger" for the judging panel. According to E! News, the final auditions for Season 15 of Idol were held on Sunday in San Francisco.
"He's going to Hollywood! Kanye West swung by to audition for our judges and of course, he got a golden ticket!! #IdolAuditions," American Idolcaptioned a video of the scene on Instagram Sunday.
West, 38; Kardashian, 34; and the couple's daughter North West, 2, were reportedly in San Francisco this past weekend for President Barack Obama's Democratic National Committee fundraiser. The rapper served as the headlining performer and then President Obama offered West some advice for his future 2020 presidential bid.
Keeping Up with the Kardashians airs Sunday nights at 8PM ET/PT on E!. American Idol is set to return in January 2016 on Fox.