The 54-year-old will return to the commercial sector.
"With the recent change of National Party leadership I have had the opportunity to consider again what I would like to do over the next several years.
"Simon has made a very positive proposal to me to stay and contribute as a senior member of the team on the front bench with a choice of portfolio.
"However I feel that it is time for him to get a new team around him to take National forward and win in 2020 and then govern again for the benefit of all New Zealanders."
Joyce told reporters he had been lucky to have a busy nine years and hoped he had made a contribution to the development of the county.
He had taken time to think over the last few days and decided it was "a fork in the road."
Joyce said he met Bridges in Tauranga this morning to tell him of his decision.
He denied it was a response to Bridges saying he would not get the finance portfolio, saying it was a personal decision.
Joyce said Bridges had not offered finance but had offered him a choice of other roles on the front bench.
He said he was not sure if he would have stayed even if he did retain the finance portfolio.
Joyce said believed Bridges would "acquit himself well" as National leader.
He said he had no regrets about standing for the leadership - and said he would offer whatever help Bridges asked for.
Joyce denied his decision to quit was a direct response to losing the leadership bid.
"I think if I was in a petulant mood I'd have gone to the backbenches and grown a beard," he said.
"The thing that made me stand for the leadership was I'm really passionate about helping New Zealanders work hard and get ahead."
Joyce said it was not easy to turn his back on that but at some point it had to be done.
He said his career had featured some interesting moments - including the sex toy thrown at him at Waitangi - but said it had been "a blast."
Asked if he regretted claiming Labour had an $11 billion hole in its numbers during last year's election campaign he said "absolutely not."
Asked for his parting words to Finance Minister Grant Robertson, Joyce said he would urge him not to forget the businesses working hard around the country.
Joyce said his crowning achievements included the national broadband rollout, saying it would help New Zealand businesses compete internationally.
His only regret was having Labour repeal National's tax cuts, saying it would mean workers on the average wage paying the top tax rate.
He did not expect he was irreplaceable, saying soon people would say "Steven who?".
Joyce would not list his mistakes: "There's actually lots of mistakes in politics and most of them never go seen."
Asked if he thought he might get a knighthood he said "Oh I don't think so."
Joyce's resignation opens the way for Nicola Willis to enter Parliament.
Willis was briefly in Parliament late last year but lost her position after the special votes were counted.
She stood in Wellington Central and is highly regarded within National. Willis previously worked as a senior adviser in John Key's office.
A decade at Parliament
Joyce entered Parliament in 2008 and went straight into a role as Cabinet Minister under then Prime Minister John Key. He had offered to assist Bridges and National.
"I have offered to assist in any way I can from outside Parliament and will remain a staunch supporter of the Party."
Joyce has led the party's general election campaigns since 2005.
"I have led the National Party's general election campaign five times as campaign chair and in four of those for John Key and Bill English, we achieved a party vote in excess of 44 per cent, the only time it has happened under MMP.
"And it was an honour to be Bill English's Associate Minister of Finance for eight years before presenting my own Budget in 2017, which continued building the platform for future economic growth and focused on boosting incomes for low- and middle-income earners.
"My plan now is to return to commercial life and seek new challenges and also to focus on being a good Dad to Tommy and Amelia."
Joyce was dubbed the "Minister of Everything" and "Super Minister" after he created the Ministry of Business, Innovation and Employment. He was Minister of Economic Development before becoming Finance Minister in 2016 after Key left.
He also gained fame for more ridiculous elements. He featured on US-based John Oliver's talk show for his assessment of the Eminemesque soundtrack National used in its 2014 campaign as "pretty legal". He also featured on the show for having a novelty dildo thrown in his face at Waitangi.
Someone John Key and Bill English turned to
The man who beat Joyce to the National leadership, Simon Bridges, thanked the departing MP for his service to the party.
"Steven has made a huge contribution during his 15-year political career, including in the last decade in Parliament. In that time he has proven an exceptional minister, colleague, advisor and political strategist," Bridges said.
"As a minister, Steven has played a major role in helping create a stronger New Zealand, particularly in the aftermath of the Global Financial Crisis."
Bridges said Joyce had played a large part in rebuilding the National Party.
"He was someone John Key and Bill English turned to for advice and to get things done. That meant he was given tough tasks but he consistently rose to those challenges. And I will also continue to use him as a sounding board as the National Party looks to 2020.
"He played a major role in rebuilding the National Party, leading the past five elections and helping turn National into New Zealand's largest and most popular political party.
"Steven is a huge loss to Parliament and to the National Party and I want to thank him for his immense contribution to New Zealand, and his wife Suzanne and their children for sharing them with us. We wish him all the best."
Former National leader Bill English said Joyce has been at the heart of the rebuild of National after 2002.
"He has made a massive contribution to his party and his country. I'm confident others will come forward to fill the huge gap he leaves in the National Party."
Labour MP and Finance Minister Grant Robertson tweeted his former rival: "All the best for the future Steven. It has been (mostly) fun sparring with you."
Robertson and Joyce had crossed swords during the last campaign over Joyce's claims of an $11 billion 'hole' in Labour's fiscal plan.
NZ First leader Winston Peters – an old nemesis of Joyce's – said Joyce's resignation was predictable.
"After all, he ran for the head job in the National Party, failed, and clearly has sought a high position even so and I don't think he's going to get it and I think this is the beginning of the in-fighting for the National Party."
He said Joyce would give the usual reasons such as family or a career for resigning "but basically this is political strife and it's shown itself and this is only the beginning of it."
He said Joyce had "certain serious qualities."
"There's no doubt about that. But being the micro-manager of a trickle down disaster is not the best legacy."
He said Joyce was "a black ops man." "And I don't like that sort of politics. We like it out front, face to face with people."
He said he would find out in the course of time whether Joyce was the leak of his super details, something Peters has said he will launch further legal action over soon.
He dismissed questions about whether he would be more open to working with National without Joyce, saying he was busy ensuring a new Government worked.
National Party President Peter Goodfellow has also acknowledged Joyce, saying he would miss his wit and leadership since Joyce became General Manager of the party in 2003.
"We are incredibly grateful for his service, knowledge, and experience over those years. National would not be as successful, united, and popular as we are today without the hard work that Steven has put in behind the scenes."
