No, Miley Cyrus has not visited Ireland—at least not publicly or professionally as of the latest available information.
In a 2013 tweet, Cyrus herself confirmed: "I've never been to Ireland but I've heard so many great things about it! I'd love to go someday."
Given her expressed interest and Ireland's strong live music market, a future visit remains plausible—but as of now, the "Wrecking Ball" singer has yet to experience the Emerald Isle firsthand.