Now, the 39-year-old is running for a seat in the Iraqi Parliament.
Zaidi likely will not win - he is running with a fringe party - but he is putting up a good fight. His shoe toss is central to his platform. His campaign's Facebook page includes a prominent clip of the incident.
"As you know me from a long time ago, I will be supporting the oppressed people and be against oppressors," he told supporters in an online video. He also promised to "sweep away" corruption and "prosecute those who steal Iraqi money."
Zaidi only recently returned to Iraq from Beirut and Europe, where he has lived since he was released from prison. At the time, he told reporters he had suffered beatings, whippings, electric shocks and simulated drownings. "I am free again, but my homeland is still a prison," he said at the time.
In an op-ed piece from 2009, he wrote about his political activism this way:
"I am not a hero. But I have a point of view. I have a stance. It humiliated me to see my country humiliated; and to see my Baghdad burned, my people killed. Thousands of tragic pictures remained in my head, pushing me toward the path of confrontation.
"The scandal of Abu Ghraib. The massacre of Fallujah, Najaf, Haditha, Sadr City, Basra, Diyala, Mosul, Tal Afar, and every inch of our wounded land.
"I travelled through my burning land and saw with my own eyes the pain of the victims, and heard with my own ears the screams of the orphans and the bereaved. And a feeling of shame haunted me like an ugly name because I was powerless."
Those horrors are still on his mind. Someday, he told reporters, he would like to run the country. His goal? Holding the United States accountable.
"I don't have any issue with America or Americans. My only issue is with the former President George W. Bush. He occupied my country, and he killed my people," Zaidi told CNN.
"If I become the prime minister of Iraq or the president then the first thing I will do is to ask the United States of America to officially apologise to all Iraqis, to compensate the victims and hold former President George W. Bush accountable."
Iraq's parliamentary elections will be held on May 12. It will be the country's first election since the Iraqi Government declared victory against Isis. According to the BBC, 24 million people are eligible to vote.