Luka Rocco Magnotta was picked up by authorities in an internet cafe in Neukoelln, a district of the German capital.
The 29-year-old is suspected of killing 33-year-old Chinese student Jun Lin, filming the murder, and then sending his body parts to politicians.
He was arrested after an employee at the internet cafe recognised him and alerted officers outside on patrol in the street.
"A colleague recognised him from his photo, because he'd just read the newspaper," said the owner, who did not want to be named.
"Nothing happened, it all went very quietly," he added.
Kerstin Zeismer, a spokeswoman for Berlin police, confirmed the arrest.
She said: "Officers arrested him on the site, he did not put up any resistance.
"He says he is the wanted person," she added, while cautioning that his identity must still be independently confirmed by German authorities.
Julie Carmichael, a spokeswoman for Canada's public safety minister, also confirmed the arrest.
Earlier, a Paris official, speaking on condition of anonymity, said police were looking into alleged sightings of the suspect in northwest Paris.
Canadian authorities believe Magnotta fled Montreal for Paris last weekend and Interpol has placed him on its most-wanted list.
CCTV images released by Interpol appeared to show Magnotta in Paris.
The murder came to light when Canadian police said a human foot had been sent to the headquarters of Canada's ruling Conservative Party.
A hand was later found in the mail at a post office in Ottawa and a torso was found in a suitcase in a pile of rubbish in Montreal.
Montreal police commander Ian Lafreniere said the victim had been "in a relationship" with the porn star, who is known to sometimes disguise himself as a woman.