The head of Waikato Mongrel Mob Kingdom, Sonny Fatupaito, was given an exemption to cross Auckland's border.
Fatupaito was allowed through to help with the Covid-19 response, assisting health authorities to reach out to "gang chapters and associated whānau", a statement from the gang's spokeswoman said.
His work started with a cluster at a South Auckland church and then extended to a chapter of the gang in the city.
"This required immediate intervention from the senior leadership in the Waikato Kingdom, and this onsite intervention ensured compliance and welfare assistance was provided as needed.
"The Kingdom has collaborated closely with providers South Seas Healthcare and The Cause Collective based in South Auckland."
Both Prime Minister Jacinda Ardern and Covid-19 Response Minister Chris Hipkins have defended the move.
Ardern told Radio Hauraki on Wednesday Fatupaito was helping with contact tracing.
"We've got cases in gangs, and that makes this job very, very hard."
Hipkins said at the 1pm Covid-19 press conference a total of two gang members had been given exemptions, as far as he knew.
"Ultimately our number one priority here is to stop Covid-19 in its tracks and that means doing what we need to do to get in front of the virus with our contact tracing and with our testing and where we’ve been able to enlist gang leaders to help with that and where they’ve been willing to do so have done that," he said.
"Look, I have no time for the gangs. I don’t have any sympathy for them, but the number one priority here has to be to stop Covid-19."
However, Simeon Brown, National's police spokesperson, said it showed there was one rule for gangs and another for everyone else.
"It is a kick in the guts for those who have been unable to cross the Auckland boundary to now hear a gang member has been designated an essential worker," he said in a statement.
"In recent weeks they’ve totally ignored the restrictions the rest of the country has been abiding by and smuggled drugs, cash, guns and even people across the Auckland boundary into the Waikato," Brown pointed out.
Meanwhile, Manurewa-Papakura Ward councillor Daniel Newman said he is encouraging those in gang communities to get vaccinated.
"The number one priority for me is to get people vaccinated and moving the dial in favour of vaccination, particularly among target population groups in South Auckland."
This included Māori, Pasifika, and younger people.
"The hard reality is stopping Covid-19 from being seeded in gang communities is vital. The public’s health is best served by having the highest possible vaccination rates, including among gang members," Newman said.
"Our clinicians teams are being run off their feet. At one high school this week we have seen Police officers and gang members lining up to help overcome Covid-19."