Coroner Ruth Thomas said the boy's death in May 2021 was a "tragic illustration of a latent hazard".
In findings released on Friday, the coroner said the boy's slat bed from The Warehouse was not inherently safe, nor is the updated model of the Living & Co bed currently for sale.
The boy's grandmother bought the pine wood single slat bed from The Warehouse in January 2021, which was the same model she had previously bought for the boy's older brother.
About two weeks before his death, the boy's bed was moved from a shared bedroom with his brother to his own room.
In the May accident, he was found unresponsive under his bed with a strap from the slats wrapped tightly around his neck and could not be revived.
Coroner Thomas ruled the boy died from ligature strangulation after a loose strap from the bed caught around his neck when he crawled underneath.
She described his death as a tragic accident.
"[He] was in his own bedroom, the room which should have been the safest room in the house for him to sleep, and to play," she said.
"There is no evidence about what time of the night or morning [he] got under his bed.
"There is no evidence about whether his death may or may not have been prevented if [he] had been checked on earlier that morning. It is unknown whether he got caught in the loose strapping during the night, the early hours of that morning, or in the minutes before he was discovered at 10am."
The 19-month-old was described by his father as an "energetic and curious little boy who liked to run around a lot".
A police inspection found the packaging box and instruction manual that came with the slat bed in 2021 did not include warning labels about the fabric straps or the risk of strangulation and diagrams in the manual did not show the fabric straps at all.
After The Warehouse was notified of the boy's death the company removed the bed from sale in its stores and online.
The coroner said the product was then updated and put back on the market.
"Since being notified of [the boy's] death in 2021, the Warehouse Group have improved the bed assembly manual to instruct the strapping is oriented on the topside of the slats, included a red warning sticker, and increased the number of staples attaching the straps to the slats. These changes have improved the amount of weight the strapping could withstand before failing," she said.
Thomas was not persuaded that the changes were sufficient.
"The most effective way to prevent the risk of strangulation from the straps attached to the bed slats is to design the problem out of existence," she said.
"[The boy's] bed was not, and the updated model of his bed currently for sale, is not inherently safe. Parents want to know the products they place in their children's bedrooms are safe."
The coroner recommended The Warehouse Group redesign the Living & Co slat bed to completely remove fabric strapping from the product and to provide warnings with the product about the risk posed by loose fabric strapping on slat beds.
In the coroner's report, The Warehouse Group said it did not necessarily agree with the statement that the updated model currently for sale was not inherently safe but it said it would work with its supplier to remove the strap from the bed design.
Coroner Thomas also recommended developing public safety messages for parents who might have never considered the hazard posed by loose straps under their children's slat bed frames.
"I acknowledge that The Warehouse Group are now working to remove the strap from the bed design," she said.
In a statement provided to RNZ, The Warehouse chief merchandise officer Carrie Fairley thanked the coroner for her report.
"Our hearts are with the family today. When this tragedy happened in 2021, our team acted immediately to enhance the bed and assembly instructions. Recently, the coroner shared further recommendations, and we're taking these on board to make sure something like this can never happen again," she said.
"None of us ever want these types of accidents to happen, and we encourage everyone to check that their beds are assembled correctly and strictly according to the instructions provided."
