Council leader Jim Logue said he ordered the move after receiving an anonymous letter relating to the council's procurement processes.
He said police had been informed and the council's audit team would now carry out a detailed investigation.
The council said that if anything was found which substantiated the claims, it would be handed over to police.
Mr Logue said: "These allegations, which are detailed, concern some of the council's procurement processes. If true, they are extremely serious.
"I immediately instructed Paul Jukes, the chief executive, to launch an investigation.
"That investigation, led by the council's internal audit team, is already under way."
The council leader said that the internal audit team would be able to access all files held by any part of the council and all IT systems.
He added: "It is essential that the people of North Lanarkshire are able to have full confidence in the way the council conducts its business and I am determined that we are transparent at all times.
"Although these are currently unsubstantiated, anonymous allegations I believe that it is right to carry out a full investigation and share any evidence which comes to light with the police.
"As that investigation is now under way, it would be inappropriate for the council to comment further."
North Lanarkshire Council has launched an investigation "into serious allegations of corruption".