The Commerce Commission said it had secured the fine over the breaches of the Fair Trading Act.
Hot water bottles need to include detailed instructions for their safe use, and children's pyjamas need to have permanent warning labels in specific locations, at the top of the garment and in online descriptions, to outline the level of potential fire risk.
"Businesses must ensure the products they supply comply with legal requirements and are safe for the intended user - especially requirements about fire safety and burns which help keep consumers safe," Commerce Commission general manager of competition, fair trading, and credit Vanessa Horne said.
"It was important for us to take this case as this is the largest number of items that didn't comply with product safety requirements the commission has seen.
"The failures in this case increased the risk of harm for the over 27,000 consumers who purchased these products."
There were 27,374 products sold between March and October 2023 that did not include safety information in the locations required by the law, she said.
This included at least 3753 children's pyjama sets that did not have the fire hazard information in the required visible spot or in the online descriptions, and 23,801 hot water bottles that did not provide instructions about safe usage and storage.
The retailer was sentenced in the Auckland District Court.
