Moise was declared winner this month of an election first held in 2015 and then redone more than a year later due to allegations of voter fraud.
Jovenel Moise was sworn in on Tuesday as Haiti's 58th president, ending a protracted electoral crisis that had created a vacuum of power in the impoverished, disaster-prone Caribbean nation.
Moise, a 48-year-old banana exporter who has never held political office, took oath at a ceremony at the National Assembly.
He was former president Michel Martelly's hand-picked choice to lead the poorest country in the Americas, one still struggling to recover from devastating natural disasters.
The election of Moise, from the centre-right Tet Kale Party (PHTK), ends Haiti's long-running political nightmare, which began in October 2015 when he first won but the results were cancelled because of massive fraud.
In February 2016, with Martelly's five-year term nearing its end and his political succession in limbo, Haiti's parliament elected Jocelerme Privert, then leader of the senate, to be interim president.
The elections were rescheduled for October and then held in November after Hurricane Matthew battered the country.
Austerity has been the motto of the inauguration ceremony, as Haiti is suffering from an economic crisis. The country is more than $2 billion in debt and anaemic growth is not expected to surpass one percent this year.
According to Moise's transition team, the inaugural costs are close to $1 million, a tighter budget than those of predecessors Rene Preval and Martelly, which cost more than $4 million and $2 million, respectively.
Moise said he had invited 53 other former presidential candidates to signal his willingness to ease political tensions. But the country's political temperature remains high, with several of his main opponents contesting his first-round victory.
The businessman is also at the centre of an unresolved money laundering probe. He denies any wrongdoing.
The investigation was launched in 2013 as a routine bank-regulation procedure. The Central Financial Intelligence Unit (UCREF) forwarded a secret report about the inquiry to prosecutors last summer.
However, the investigating judge took no action until four opposition senators recently demanded information about the findings. The investigating judge delivered conclusions to the government prosecutor who has made no public announcements on the case.
The suspense undermines Moise's already fragile popularity.
He was declared the winner with 55 percent of the votes, but with a dismal turnout of just 21 percent.
Haiti is still struggling to recover from the world's most significant cholera outbreak, with an estimated 30,000 cases expected this year, as well as the effects of the January 2010 earthquake, with tens of thousands of people still camping in tents without proper sanitation.
The government and aid officials said Monday that Haiti needs nearly $300 million to provide urgent assistance for its most vulnerable inhabitants, including those affected by Hurricane Matthew last October.
Four months after being battered by the massive hurricane, which caused $2.8 billion in damages, more than 1.5 million people remain in dire need of humanitarian assistance, said El-Mostafa Benlamlih, representative of the United Nations Stabilization Mission in Haiti (MINUSTAH).