The 25-year-old singer voiced her love and respect for the "Chun-Li" rapper in a new interview with Paper magazine.
"She is my sister, and I have so much respect for that woman because she puts up with a lot," Grande said. "And I think she is one of the greatest rappers of all time, male or female."
"It's kind of wild that people still try to discredit her and question what she's done and accomplished. Everything that she does is spectacular," she added. "She has a gift and she is a spectacular artist."
In addition to Minaj's talent, Grande had good things to say about the rapper's personality.
"I think as a human being, there is the most beautiful soul underneath this really badass exterior. And it's really an honor to know that girl, cause she's really tight and I love her," she said.
Grande and Minaj have collaborated on several singles, including "Side to Side" and "Bed." Grande previously voiced her love for Minaj in a series of tweets in May.
"i love my big sis @nickiminaj," she wrote. "there's jus nobody better."
Minaj postponed the North American portion of her NickiHndrxx tour this week following rumors of low ticket sales. She accused Travis Scott and Kylie Jenner of undermining her album Queen in a tweet Sunday.