Mr Littleproud will remain in parliament as the member for Maranoa, saying he loved representing the people of regional Queensland but it wouldn't be right for him to continue at the helm of the party.
"I'm just buggered," he told reporters in Canberra on Tuesday during an emotional press conference alongside his wife Amelia.
"It'd be wrong for me to say that I'm the right person to continue to lead. That's tough for me to say.
"I think someone better can do it, because I don't have the energy."
Mr Littleproud said he wanted to spend more time with his family but he still loved coming to parliament, which was why he wasn't resigning entirely.
"I want to come back to this place as I did when I first got into parliament, with that spring in my step, the excitement of coming here, throwing a few grenades, having a couple of beers and enjoying myself, and I haven't had that for a while," he said.
Matt Canavan, one of the regional party's most outspoken members, on Tuesday became the first to throw his hat in the ring for the party's top job.
But there is no clear successor for the leadership with deputy Kevin Hogan, the party's Senate leader Bridget McKenzie and former leader Michael McCormack among other potential contenders.
Senator Canavan thanked the outgoing leader as he announced his candidacy on social media.
Senator McKenzie wouldn't buy into whether she would run for the leadership.
"David's just resigned and I think it is on all of us to actually reflect on his service, it's not easy to lead a political movement, particularly after such a devastating loss at the last election," she told ABC TV.
A Nationals party room meeting will be held by the end of the week to select a new leader.
Mr Littleproud first entered parliament in 2016, representing one of the safest seats in the country and took over the Nationals' leadership after the coalition's 2022 election defeat.
He courted controversy when he announced he would not renew the coalition agreement with the Liberals after the 2025 election, citing policy disagreements.
The parties reunited but split again in January following a dispute over hate speech laws, before getting back together weeks later.
The Nationals have been under pressure from One Nation as it rises in the polls, with former leader Barnaby Joyce defecting to Pauline Hanson's party in December.
Mr Littleproud survived a leadership challenge from Queensland backbencher Colin Boyce in February.
Opposition Leader Angus Taylor paid tribute to the outgoing Nationals head, acknowledging him as a man of his word and saying he had played a critical role in shaping the direction of the coalition.
"David is a man of great dignity who has led his party with great energy and commitment," he said.
Prime Minister Anthony Albanese wished Mr Littleproud well.
"It is a significant achievement to be chosen to lead your party," he said in a statement.
"David can look back on his four years as leader of Nationals and 10 years as member for Maranoa knowing he has given his utmost."
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