Lemieux's manager Camille Estaphan said Monday that no date has been set, but he expects the bout to be held in Montreal, his fighter's home town.
"It's a dream come true for any boxer to fight for a world title," said Estaphan. "We feel he's ready."
The title was stripped from Jermain Taylor two weeks ago after the American was charged with aggravated assault, endangerment of a minor and other offences from an incident with a man and his family in August.
N'Dam N'Jikam (31-1, 18 knockouts) is the IBF's top contender while the power-punching Lemieux (33-2, 31 KOs) is ranked fifth.
It is to be Lemieux's first fight since he signed in January with Golden Boy Promotions, a California company run by former ring great Oscar de la Hoya.
His former promoter, Groupe Yvon Michel, said it would take any legal means possible to try keep the fighter, saying that Lemieux was still under contract. Michel was angry that 26-year-old Lemieux opted to leave just as he was ready to challenge for a world title.
Estaphan said Lemieux's deal with GYM ended in 2013.
"I'm not concerned at all," he said.
Estaphan pushed for the bout when the IBF gave it's blessing and Golden Boy's people said they were in favour of having it in Montreal.
Lemieux wrote on Twitter: "Let's do it. The fight is on. N'Dam U can run but I'll catch U."
The 30-year-old N'Dam N'Jikam will be a tough opponent.
The France-based fighter's only defeat came in a world title fight, a loss by decision to Peter Quillin for the WBO belt in 2012 in New York. He had won the interim WBO title five months earlier with a decision over Max Bursak in France.
N'Dam N'Jikam is coming off a win in October over Curtis Stevens in California.
Lemieux has bounced back from his only two defeats in 2011 to fellow Montreal fighter Joachim Alcine and Marco Antonio Rubio with an impressive run of wins. He got rave reviews for his latest outing, a 10th round TKO of Gabriel Rosado, to keep his North American title in New York on Dec. 6.
He was looking for a higher profile bout with a champion from one of the other three main sanctioning bodies, but none could be arranged with Gennady Golovkin of the WBA, Miguel Cotto of the WBC or Andy Lee of the WBO; or with Mexican star Canelo Alvarez.
Lemieux is a crowd-pleaser known to neglect defence to try to win with dazzling speed and knockout power.