Aristide was welcomed by large crowds of supporters. His arrival comes just days before Haiti's presidential runoff election. Aristide himself was twice elected president and twice deposed.
Though he remains popular for his support for the poor, he also has many critics who say he led a corrupt and violent government.
Election laws bar him from running for president, but his return could influence the election's outcome.
Aristide's political party, the Lavalas Family, is barred from the presidential election as well, and the former president did not hide his disapproval regarding that decision.
"Excluding Lavalas, you cut the branches that link the people," he said in remarks that were otherwise largely devoted to thanking supporters who stayed loyal to him during his exile and helped engineer his return over the objections of the U.S. government. "The solution is inclusion of all Haitians as human beings."
Haiti's electoral council barred Lavalas from the elections for technical reasons that its supporters say were bogus. Many of its members are boycotting Sunday's runoff election. Still, several people affiliated in the past with the now-less prominent party ran in the first round of the election.
The initial election on Nov. 28 was so clouded by fraud, disorganization, voter intimidation and violence that 12 of the 19 candidates, including the front-runners, initially called for it to be tossed out.
In exile, Aristide has been reclusive, doing university research and polishing his academic credentials with a doctorate awarded by the University of South Africa for a comparative study of Zulu and Haitian Creole.
The Associated Press contributed to this report.