Mr Perrottet, 41, also served as coalition treasurer and minister for both industrial relations and finance before winning the state's top political job in 2021.
"I love NSW," he said in a statement on Friday.
"It has been an absolute honour to represent the eight million people who call this great state home, especially as their 46th premier."
The father-of-seven, his wife Helen and their children are moving to the United States where he has accepted a global role as BHP's US head of corporate and external relations.
At age 39, Mr Perrottet became the youngest premier in the state's history after the resignation of Gladys Berejiklian.
He served for almost 18 months, coming into the role as NSW emerged from months of COVID-19 lockdowns, before Labor took office at the March 2023 election.
Mr Perrottet, who is giving up his lower house seat of Epping, has previously been touted as a potential federal Liberal candidate.
"I got into politics to promote ideas and new ways of thinking and I am proud to have been part of a government that left NSW in a much better place than we found it," he said.
His departure sets the scene for NSW Liberal party to face two by-elections, after Hornsby MP Matt Kean announced his resignation in June.
Mr Kean was treasurer in Mr Perrottet's government.
Dominic Perrottet with family during a campaign rally for the 2023 state election. (Jane Dempster/AAP PHOTOS)
Mr Perrottet plans to give his valedictory speech when state parliament returns in August, before formally resigning on August 11.
Opposition Leader Mark Speakman said Mr Perrottet had left an indelible mark on NSW.
"He was a reformer who had a passion for new ideas and imagination for what would make NSW a better place for all," he said.
Mr Perrottet's five budgets delivered strong surpluses and record infrastructure investment, driving the state's asset recycling program and establishing the NSW Generations Fund, valued at more than $17 billion.
"His legacy is one of remarkable achievements and steadfast leadership," Mr Speakman added.
Premier Chris Minns congratulated Mr Perrottet for all he did for NSW and wished him luck.
"Dom leaves behind a huge legacy in our state both as a reforming treasurer and premier who spearheaded city-shaping projects," he said.
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