Acting Wairapapa area commander Detective Inspector Scott Miller said on Thursday that ongoing enquiries as part of Operation Sweden had led to the massive drug haul and three further arrests on Wednesday night.
Of the three arrested, who were all on the police's radar, two had links to Wairarapa.
One person arrested in Auckland was found to be in possession of $40,000 cash and 30kg of methamphetamine, an amount which would have a street value of between $20m and $30m, depending on how it was sold.
Mr Miller said "that was the largest seizure of meth that we've ever had" come out of a Greater Wellington-based police operation.
"We were expecting a sizable haul of methamphetamine, but that was beyond our expectations."
Police are not yet certain where the drug was manufactured, but say it was "professionally packed".
The seizure would make a "huge dent" in the distribution of meth in the Greater Wellington region and Auckland.
"A small percentage would've ended up in Wairarapa, that's our belief, at the moment, that's what we think."
Detective Senior Sergeant Barry Bysouth said methamphetamine was usually sold in measurements of points, with "a point" being a tenth of a gram.
A point would fetch between $80 to $100, depending on the quality.
The two other people who were arrested on Wednesday in connection to Operation Sweden were picked up in Wairarapa and Wellington.
The Wairarapa arrest revealed 140grams of meth and $3000 in cash, while the Wellington arrest resulted in $40,000 in cash and 14grams of the class-A drug being seized.
Having identified "one of the biggest meth syndicates in Wellington", there would be a dramatic reduction in crime.
Mr Bysouth said every "point" of meth taken off the street meant there was the potential for one less "burglary, stolen car, or stolen chainsaw from a shed".