The National Trust handed the keys to Parc Farm on the top of Llandudno's Great Orme to 38-year-old Dan Jones from Anglesey in October.
The site has rare habitats and species - some of which the charity said existed nowhere else on Earth.
The 360-strong flock will graze on the grassland to encourage the survival of rare plants and animals.
Sheep have not been seen on the headland since the foot and mouth crisis more than a decade ago.
Property manager William Greenwood said: "If we get this right, we should see the rarer species such as the silver studded blue butterfly and wild cotoneaster, which exist only on the Great Orme, really flourishing."
A tenant who took on a £1m farm in Conwy county for just £1 a year rent is to reintroduce sheep to its headland.