The award, the highest honorary distinction in the West African country, was conferred on Ahmadinejad for his role in supporting the movement of non-aligned countries.
"To appreciate your work as the chairman of the movement of the non-aligned countries and to encourage you to continue working for the movement, Benin has decided to award you the National Order of the Great Cross," Yayi said.
Receiving the award, the Iranian president thanked the people of Benin and the country's leadership.
"I thank the people of Benin and their president for this gesture which represents a symbol of long lasting friendship between the Iranian people and the people of Benin," he said.
Ahmadinejad said Benin and his country are two influential members of the non-aligned movement who should cooperate in all domains for their economic development.
"I am convinced that our bilateral relations in all domains, especially in the economic domain, will develop as much as possible," he said.
The Iranian political leader said "only peace, security and progress should characterize the contact between the two countries. "
Ahmadinejad began a two-day official visit to Benin on Sunday to reinforce the bilateral relations established in 1983.
After Benin, he is scheduled to visit Ghana and Niger.