The combined organisation will be known as The Security Institute, and the current Security Institute chairman Bill Wyllie will become chair of the whole organisation.
John Rose from the IIS will become deputy chairman, and David Gill will remain as vice-chairman. The finalisation of the merger talks was announced late on Wednesday afternoon.
One of the new initiatives to come out of the merger will be the establishment of an academic board to work towards further incorporation of academic standards into professional security life.
The new organisation hopes that the merger will also help its petition for chartered status.
Commenting on the merge, Wyllie said that the merger was a step forward in driving up standards.
“This is an historic and exciting development in the drive for professional standards and recognition in the business of security.”
He added: “The Security Institute will continue to work with government, national agencies, the business sector, other professional organisations and people across society, in order to deliver the highest standards of professional competence and integrity.”