Oneroa may refer to:
- Oneroa, Cook Islands, located on Mangaia
- Oneroa, New Zealand, located on Waiheke Island
Oneroa is a Cook Islands electoral division returning one member to the Cook Islands Parliament. Its current representative is Winton Pickering, who has held the seat since 2004.
The electorate consists of the districts of Keia, Tavaenga, and Veitatei on the island of Mangaia. It was created in 1981, when the Constitution Amendment (No. 9) Act 1980 adjusted electorate boundaries and split the electorate of Mangaia into three.