The report from the Catholic Land Pastoral, indicated there were 280 cases debt slavery reported in 2008, a 6 percent increase over 2007.
The report - relying on government data - also showed that 36 percent of those cases were linked to sugarcane production, which drives Brazil's much-lauded production of ethanol.
Debt slavery is common in Brazil's Amazon, where poor laborers are lured to remote spots where they rack up debts to plantation owners who charge exorbitant prices for everything from food to transportation and force the workers to sleep in cramped quarters.
While the number of reported cases of debt slavery jumped, so did the number of people freed by government agents who raid remote plantations in Brazil's most sparsely populated areas.
At least 5,266 people were freed by authorities last year - 48 percent of whom were working on sugarcane farms, according to the Catholic Land Pastoral.
Brazil's association of sugar and ethanol producers, declined to comment on the report. Brazil's Agriculture Ministry had no immediate comment.
The work of the elite Mobile Verification Task Force, which raids farms and frees workers mired in debt slavery, has been a political hot-button in the past. In 2007, the unit went on a two-week strike to protest congressional criticism and interference in its work on leading ethanol producers.
Since its creation in 1995, the task force has freed more than 30,000 workers nationwide from debt slavery. The CPT has estimated that at least 25,000 Brazilians continue to toil in debt slavery conditions.