In a country marred by poverty and political instability, he became the only democratically-elected president to serve two separate full terms.
Mr Preval was first elected in 1995 but it was during his second term that he faced his biggest challenge.
Haiti was hit by a powerful earthquake in January 2010, which killed up to 300,000 people.
The quake destroyed much of the capital, Port-au-Prince, and displaced at least one million people.
Haiti, which is the poorest country in the Americas, has struggled to recover from the tragedy.
Haiti has been politically turbulent for much of its history since winning independence from France in 1804.