Helensville was a New Zealand parliamentary electorate in the Auckland region, returning one Member of Parliament to the House of Representatives. The electorate was first established for the 1978 election, was abolished in 1984, and then reinstated for the 2002 election. The seat was won and held by John Key through his term as prime minister. Chris Penk of the National Party held the seat from the 2017 general election until its abolition in 2020, when it was replaced with the new Kaipara ki Mahurangi electorate, which Penk also retained.

The 1978 New Zealand general election was a nationwide vote to elect the 39th New Zealand Parliament. It saw the governing National Party, led by Robert Muldoon, retain office, but the opposition Labour Party won the largest share of the vote. Reorganisation of the enrolment system caused major problems with the electoral rolls, which left a legacy of unreliable information about voting levels in this election.