American Idol just got (slightly) more interesting again after years of popular and creative decline.

Mariah Carey, one of the most commercially successful recording stars in pop music history, has agreed to join the judges’ table for Season 12, which will begin airing on Fox in January.

The not-altogether unexpected move was announced at the Television Critics Association Press Tour in Los Angeles Monday and ended some speculation as to who could best fill slots vacated by Jennifer Lopez and Aerosmith singer Steven Tyler earlier this month.

In terms of star power and appeal to the average Idol contestants who have been trying to mine her vocal style for 11 years, Carey dwarfs any judge who has previously endured auditions of her songs Hero, Vision of Love or her cover of the Jackson 5’s I’ll Be There. Though her album sales have slipped in recent years, Carey is still a bigger prize for Idol than such departed judges as ’80s pop star Paula Abdul, talk show comic Ellen DeGeneres, JLo, Tyler or even British music exec Simon Cowell, who became Idol’s first real breakout star in America thanks to his acidic criticisms of tone-deaf aspirants.

The hiring could also stem the dip in Idol’s, ratings which fell by 23 percent this year — though even with that plunge the singing competition show still drew about 18 million viewers and often was television’s No. 1 program, swapping that honor with procedural NCIS or Dancing With the Stars. Idol remained far out front in total viewership over such challengers as NBC’s The Voice, ABC’s Duets or Fox’s underperforming, headache-inducing The X Factor with Cowell.

“As a singer, songwriter and producer, it’s going to be fun and rewarding to help find new talent and give back with American Idol,” Carey, 42, said in a statement, reported in Rolling Stone. Carey has scored 18 No. 1 U.S. Billboard singles, putting her in Elvis and Beatles territory in the trades.

The real winner in this equation could be Randy Jackson, the sole original judge who was rumored to be shifting into mentoring status amid a major overhaul next season. Jackson manages Carey and was reportedly involved in her negotiations so he almost certainly stays. Could be fun to see if they disagree on the panel.

Curiously, Idol Season 8 runner-up Adam Lambert could also stand to benefit.

Lambert, 30, has seen his name mentioned in the press as a possibility for the judges’ table (though nothing is official.) Given that Carey will reportedly make $18 million for her services, the show isn’t likely to hire another A-list pricey star for the third seat. (Carey’s paycheck tops Britney Spears’ salary of $16 million as a judge on The X Factor, making Carey the highest paid singing competition judge on TV.)

Lambert’s fans, the Glamberts, take to Twitter in Olympics-worthy time to blindly defend their boy for any post that falls short of calling him the greatest pop star to ever walk the earth. But the indisputable facts are his album sales post- Idol have been unspectacular, and pop radio has embraced only one of his singles from his two albums . Compared to an A-lister like Carey, he could be an affordable option, and his edge on the panel would be welcome.

Aretha Franklin, 70, has said she wants the gig, too, but with Carey aboard, two female icons is unlikely.

We might know who Carey’s fellow judges are within a week.

Meantime, the Season 11 finalists perform at Sunrise’s BankAtlantic Center Aug. 3.

Howard Cohen

Follow @HowardCohen on Twitter.