Carey, 42, one of three new judges to join the Fox talent show's new season on Jan. 16, told Barbara Walters in an interview that aired Monday night on "Nightline" that "it felt like an unsafe work environment."
"Anytime anybody's reeling threats at somebody, you know, it's not appropriate," Carey said.
"I'm a professional. I'm not used to that type of environment," she said, adding that she hired extra security.
Minaj, a Trinidad-born singer and songwriter, previously denied making any remarks about firearms, but Carey told Walters that beefing up her security "was the appropriate thing to do."
"Sitting there on the road with two babies, I'm not going to take any chances," Carey said, referring to her 20-month-old twins with husband Nick Cannon.
But in a sign of media savvy, she noted that "for all the drama, I hope it helps the show."
Walters also asked Carey about reports that she is being paid $18 million for each "Idol" season.
"I think we're in the ballpark, [but] I can't even talk about those things," the singer replied.