The National Distribution Union says it has seen considerable growth in recent months, particularly among retail workers.
It says in the past three months its membership grew by a thousand to over 23,000, on the back of a thousand new members in the previous year.
The NDU believes it means unions remain relevant as ever, for protecting workers' rights and winning pay increases to help members keep up with rising living costs.
Around 380,000 New Zealanders are currently members of a union.
- Newstalk ZB