"We have agreed to follow the same path of fighting against imperialism and to strengthen our cooperation in eliminating America's domination in the world," he said after a meeting with the Iranian president.
Chavez described Ahmadinejad as "a great anti-U.S. fighter" and "a champion of truth and social justice." The Iranian leader responded by calling Chavez "a great revolutionary of Latin America."
Ahmadinejad, on his third visit to Venezuela, said that imperialism "has no other option but to start respecting the people's choice, or it is doomed."
Hugo Chavez has made five visits to Tehran, the last in July 2007. He has repeatedly stated his support for Iran's nuclear research program.
Ahmadinejad met earlier Friday with Bolivian President Evo Morales, signing a $1 billion trade and energy cooperation agreement.