In Berlin, the crowd was largely pro-union and anti-capitalism.
"We have more rich and even richer people than we ever had before," protester Aimo Tuegel told the Associated Press. "On the other hand, work and working conditions for workers are continuing to get worse."
Hooded and masked anarchists were in the Parisian streets too, smashing windows, throwing cobblestones, and lighting cars on fire.
More than 200 protesters were arrested and at least four people, including one police officer, were injured in the violence, Reuters reported.
In Istanbul, some protesters shouted "long live May 1."
Dozens of people were detained in the Turkish city after trying to enter a square the police deemed off-limits to protests, according to the Associated Press.
Neo-Nazis and far-right leaning groups in Germany have also started using the day to stage demonstrations of their own.
Violent clashes between left and right-wing protesters have been breaking out on May 1 in cities like Hamburg and Berlin for decades, according to Deutsche Welle.