The opening of the ACTe memorial on the site of a former sugar refinery that processed the products of slave plantations "will allow Guadeloupe and the whole of the Caribbean, with a deep bond with Africa, to tell the world that the combat for human dignity is not over", Hollande said on Saturday ahead of the inauguration.
He cited the people smugglers in the Mediterranean and the recruiters of child soldiers as some of the "new slave-traders".
The memorial, a newly built building overlooking the bay of Guadeloupe's main town, Pointe-à-Pitre, looks at the history of slavery from antiquity to the modern day and pays homage to slave revolts and runaways who established free communities in the New World.
Its cost - 83 million euros - has aroused criticism on an island with serious economic problems, although local officials hope it will help attract tourists to the island.
"Today Guadeloupe means 60 per cent of under-25-year-olds unemployed, practically 30-33 per cent of the working age population unemployed, an illiteracy rate of more than 25 per cent of the population," trade unionist Elie Domota, who led a general strike against the rising cost of living in 2009, told France Inter radio.
He called for abrogation of laws passed in 1848 and 1849, which compensated slave-owners for the abolition of slavery.
The ceremony - attended by Senegal's President Macky Sall, Mali's Ibrahim Bouboucar Keïta and Benin's Thomas Boni Yayi - was to be broadcast live at the Jardin du Luxembourg in Paris, where Prime Minister Manuel Valls attended the government's official event to mark the day.
American Communist Party activist and veteran black rights activist Angela Davis was to receive the freedom of Nantes, France's main slave port before abolition, on Sunday, while another former slave port, Brest, inaugurated a 10-metre-high sculpture, entitled Mémoires, with two faces, one looking out to the Atlantic, the other towards Europe.
Several activists' groups in the French West Indies and in France have launched legal cases for compensation for the trade.
One of them, the Cran, announced on Saturday that it has filed a case for profiting from crimes against humanity against the former head of employers' union Medef, Ernest-Antoine Seillière, who was also boss of the Wendel group, an investment fund founded by his ancestors that had interests in plantations and slave ships.
"The descendants of slave traders are not guilty but they have profited from it and their fortune comes from ill-gotten gains," commented Cran president Louis-Georges Tin. "In refusing compensation, they make themselves liable for the crime that they are vainly trying to dissociate them from."