In a decree on Thursday, Ayatollah Khamenei said the appointment is based on Article 176 of Iran’s Constitution, which outlines national security responsibilities.
The Leader expressed gratitude to Ali Akbar Ahmadian for his great efforts in the post in recent years.
The replacement comes after Ahmadian was tasked with carrying out important executive responsibilities, Ayatollah Khamenei said.
With the Leader’s appointment, Larijani replaces Ahmadian as one of Ayatollah Khamenei's two designated representatives to the body. Saeed Jalili is the other representative currently serving in that capacity.
On Tuesday, President Masoud Pezeshkian appointed Larijani as the new secretary of the SNSC, replacing Ahmadian, who had served in that role since May 2023.
Leader appoints Ahmadian, Shamkhani as representatives to Defense Council
In a separate decree also on Thursday, Ayatollah Khamenei named Ahmadian and Ali Shamkhani, also a former SNSC chief, as his representatives to the Defense Council.
The appointment comes after the Supreme National Security Council approved the establishment of a Defense Council as part of major structural changes to the nation's strategic defense policies.
The Defense Council is responsible for developing defense strategies and enhancing the capabilities of the Armed Forces.
The Iranian president will head the Defense Council, which also includes the heads of the three branches of government, senior military commanders, and designated ministers relevant to defense affairs.