Mr Gilmore said that staying on in Parliament would "only serve to cause my loved ones more upset, and cause me undeserved further stress".
Prime Minister John Key welcomed the decision as the right one "for himself, his family and the National Party".
National Party president Peter Goodfellow said: "Aaron has had a tough decision to make. Today, he has put his loyalty to the party first in announcing his intention to resign his list seat."
Mr Gilmore was in Christchurch over the weekend spending time with his family, while other National MPs attended a party conference in Wanganui.
He said he had decided to resign "after taking counsel from colleagues and family".
Pressure on Mr Gilmore to resign intensified late last week after it was revealed he was warned about sending inappropriate emails while working at a government department - an allegation he had previously denied.
That was just a few days after Mr Key made it clear he thought Mr Gilmore should resign after a text message exchange between Mr Gilmore and his dining companion at Hanmer Springs, Andrew Riches, emerged which undermined what he had told Mr Key's office about the evening.
Mr Gilmore said media scrutiny in recent days since reports of his night out in Hanmer Springs where he was abusive to a waiter had "put me and those who are important to me under immense pressure with an attempt to discredit me".
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