The holiday will apply across the private and public sectors, Oman news agency (ONA) reported on Wednesday.
Sultan Haitham succeeded Sultan Qaboos bin Said ― who ruled Oman for 50 years ― in 2020.
On his second anniversary as ruler, Sultan Haitham spoke about the job opportunities his country had provided for Omanis despite struggles and fall-out from the Covid-19 pandemic.
Almost a year later, at a cabinet meeting on Tuesday, Sultan Haitham gave orders to "consolidate investment and diversify its sources" to boost investor confidence in Oman.
During the session, he also emphasised the need to generate jobs for Omanis and encourage young people towards entrepreneurship.
"The Sultan instructed the departments concerned to offer the appropriate environment for citizens to take all types of jobs and enterprises," ONA reported.
Earlier this week, Sultan Haitham approved 11.35 billion rials ($28.34 billion) in spending this year, including the biggest increase in social security budgets in six years.
People took to social media to congratulate Sultan Haitham before the anniversary.
"May God protect His Majesty, provide him with good health and well-being," one Twitter user by the name of Abdullah Alawaid wrote along with a photo of Sultan Haitham.
Another, Emad, wrote: "May God protect the Sultan of Oman Haitham bin Tariq. Loyalty to who watched over the country, harnessing his capabilities in service of the nation."