Jack and Stelly announced last Thursday that they recently became engaged, with Kelly later tweeting that she's "unbelievably proud" of her younger brother.
Kelly has now revealed that Stelly is the only one of Jack's girlfriends that she has ever approved of.
"I have to admit to you, she's the only girl my brother has brought home, that I've ever actually really liked and not had to pretend to like," she joked to Access Hollywood Live.
Kelly went on to wish the best to the young couple, saying: "I really, really like her, she's awesome and they're really, really sweet together. I'm so happy for them."
Watch Kelly Osbourne discuss Jack Osbourne's engagement below:
Kelly has credited her brother Jack with helping their father Ozzy Osbourne get sober.
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