Community-based organisations or environmental groups by and large lacked the money to try curry favour with politicians in such a manner, Shaw said.
• READ MORE: Selling influence: meet the lobbyists shaping New Zealand politics for a fee
"They're not usually organisations who advocate for the homeless or for single mums; or groups that are fighting to protect our water, or our native bush.
"They're not organisations that have stopping climate change or ending child poverty as part of their KPIs."
Shaw said political power should not be for sale.
"The Green Party has always stood for more transparency around lobbying and access to politicians.
"Now we're in Government, we think it's important to take the lead on this issue, and to try to counter some of the influence of money in politics."
Green Party MPs, Ministers and staff will be able to accept invitations to events, but they will pay full price for their tickets.
Similarly dinners, lunches or coffee meetings will be paid for by the party "where we can".
Shaw also announced he and fellow minister Julie Anne Genter, Eugenie Sage and Jan Logie would all start releasing their ministerial diaries every quarter, to show who they've met with and why.
Calling transparency a hallmark of democracy, Shaw said citizens think New Zealanders deserved to know who was meeting with MPs and ministers, and what the purpose of those meetings were.
The Green Party's Lobbying Disclosure Bill was drawn from the ballot but rejected in 2013 by a parliamentary committee over concerns it was too broad.
Originally drafted by former Green MP Sue Kedgley in 2011, the bill would have forced lobbyists to register and disclose their clients and meetings with Government ministers.
Shaw mentioned in his speech today that the Greens had long been a progressive party dissatisfied with the status quo.
Now they had access to the levers of Government, the Greens could affect "real progress on the issues that have defined us as a party".