Two of the men have been seriously injured, and all are receiving medical treatment.

The men's convoy was ambushed near Macmahon's operations in Nigeria last Wednesday and a local employee was shot dead.

Three Australians, two Nigerians, a New Zealander and a South African were kidnapped.

Arrangements have been made for the men to return home, once they receive medical clearance to travel.

Macmahon CEO Sy van Dyk said the men had displayed courage throughout the ordeal.

"Our men have been through a traumatic experience, and we have mobilised medical and other support teams in Nigeria to provide immediate support," he said.

"The families have all been informed of the successful release of the men and have had the opportunity to speak to their loved ones."

Van Dyk praised the men's families for working closely with the company through a stressful experience.

He said Macmahon's dedicated team had worked around the clock to secure the men's release.

"While we are relieved to be able to reunite the seven men with their loved ones, we are deeply saddened by the loss of the local driver Matthew Odok, who was fatally injured during the initial incident," van Dyk said.

Van Dyk thanked the Nigerian, Australian, New Zealand and South African authorities, as well as the security advisors who had supported the company.

"This has been an incredible team effort and our highest priority now is to finish the job by continuing to work together to get our people back safely to their families and homes," he said.

"While we understand the media's interest in these developments we ask that the privacy of all the families be respected at this time."

It is unclear if a ransom was demanded or paid.

Macmahon has a 6.5-year, $US105 million contract to perform all limestone mining activities at Lafarge's Ewekoro cement plant in Nigeria.