Of the 22 arrests nationally, which included seven patched Mongrel Mob members, there were 14 arrests in the Marlborough region alone.
At a Nelson address a large quantity of plastic bags commonly used for the distribution of methamphetamine, with Mongrel Mob insignia printed, on them were recovered.
Quantities of cash, about 1kg of dried cannabis and 24 plants, more than 9g of methamphetamine, a firearm, stolen computers and drug utensils have also been recovered.
Young children were present at some addresses and police have made three referrals to CYF.
A total of 250 charges have been laid. They include possession of class A and C drugs for supply; conspiring to supply or deal methamphetamine; conspiring to supply or deal class C and B drugs; offering to supply methamphetamine; offering to supply class B and C drugs; possession of class B and C drugs, theft, and burglary.
Police say further charges and arrests are likely.
Marlborough area commander Inspector Simon Feltham said a team of police in Blenheim had put in "an enormous amount of work'' gathering evidence about the gang's drug dealing activities and that had led to further offenders being identified outside the Marlborough area.
"Since the Mongrel Mob turned up in Marlborough, police have been vigilant in monitoring their activities,'' he said.
"Neither police nor the Marlborough community are prepared to tolerate their drug dealing.
"This operation has resulted in the arrest of all of the senior members of this criminal group in Marlborough and it sends a very clear message to their associates that they are not, and never will be, welcome here.''