“We were able to register around 46 million voters,” Corneille Nangaa said, a day before unveiling the register that will form the basis of voting records in the crucial December 23 vote.
Nangaa said the process had allowed election officials to identify “millions of duplicates”.
Other election officials put the figure at around 6 million duplicates or children who had registered to vote since January 31.
The voting register unveiled on Friday will form the basis of seat distribution in local elections, due to be decided by May.
President Joseph Kabila was due to stand down from office when his second term ended in December 2016. But he has controversially stayed on under laws enabling him to retain power until a successor is elected.
The latest timetable to hold elections is for December 23 — a year later than scheduled under a New Year’s Eve 2016 peace deal brokered by the Catholic Church.
Kabila has refused to state clearly whether he intends to stand again and fears have multiplied that the country, which experienced wars from 1996-97 and from 1998-2003, could explode into violence once more.
This has sparked protests and a brutal crackdown with at least 15 people have been killed in two marches in December and January where police fired tear gas and live bullets, according to the UN and church authorities.
In addition to a deepening political crisis, the DR Congo is struggling with armed conflict in its vast, resource-rich east, which is under the sway of multiple rebel groups.