“The results (of the counter-insurgency) are impressive” and the rebels had been “diminished and forced to retreat”, he told a news conference in Abuja where he is to take in the regional security summit.
But added: “This terrorist group nevertheless remains a threat.”
Hollande spoke after holding talks with President Muhammadu Buhari at the presidential villa before regional leaders met to discuss the conflict.
Discussions at the security summit are expected to focus on the formal deployment of a new regional force comprising troops from Nigeria and its neighbours Benin, Cameroon, Chad and Niger.
Over the last 15 months, individual armies have largely been acting independently to curb the violence in the face of mounting cross-border attacks, particularly suicide bombings against civilians.
The UN Security Council has also raised concerns about Boko Haram’s links to the Islamic State group, after reports of Nigerian fighters in lawless Libya.
Buhari said progress had been made, as Boko Haram, which captured swathes of territory in 2014 and declared a self-styled caliphate, was “now… not holding” any local government districts in the northeast.
But he said the “main problem now is rehabilitation” of destroyed infrastucture such as schools, health clinics, roads and bridges, as well as handling the displaced, more than 60 percent of whom are women and children, many of them orphans.
“This is a pathetic situation and is a major problem we are going to face in this country.”
Hollande, who sees France as a natural liaison between its former colonies and English-speaking Nigeria, said results had been achieved through better regional coordination.
Paris had also provided training and equipment, he added, as part of the international support to Abuja that includes British military trainers and US surveillance drones.
Hollande and Buhari signed a “letter of intent” to pave the way for a defence agreement.
The two leaders also signed several accords strengthening existing cooperation, including through France’s main development agency, of upwards of $120 million (106 million euros) for Nigeria’s under-capacity electricity sector.