More than 20 years later, he was installed as the puppet leader of Japanese-occupied Manchuria, before he was captured in 1945 after the fall of Japan and taken to a Soviet prison camp.
British auction house Phillips said it had documentation that showed Puyi had brought the watch with him to the camp.
It was expected to fetch about $3 million but, after about five minutes of spirited bidding, it was sold for HK$40 million ($5.1 million). With the commission fee, the total price came to about $6.2 million.
Thomas Perazzi, Phillips' head of watches in Asia, said he was "thrilled with this groundbreaking sale" because it set records.
Those records included "the highest result of any Patek Philippe reference 96 ever sold", according to a news release.
The Ref 96—austere compared to the usual luxury pieces on sale in auction houses—was the first complication wristwatch serially produced by Patek Philippe, with Perazzi saying there are currently only "three examples known" in the world.
According to the memoir of Puyi's nephew Aisin-Gioro Yuyuan, the watch was a "personal item" of the deposed emperor, who passed it to his Russian interpreter Georgy Permyakov for safe-keeping when he left the prison camp.
Russell Working, a journalist who interviewed Permyakov more than 20 years ago, told AFP that the elderly interpreter had no idea of its value when he pulled the timepiece from his drawer.
"To have this one surface all of a sudden after all these years, it was like a treasure chest washing up on the beach," said Working, who was part of the auction house's research team.
Another item on auction was a red paper fan, inscribed with a poem by Puyi "dedicated to my comrade Permyakov". That fetched more than $77,800—six times its pre-sale estimate.
Puyi's watch, while historically significant, is far from the most expensive timepiece ever sold on the auction block.
A Patek Philippe "Grandmaster Chime" sold for $31 million in 2019. It is said to be the most complex timepiece the luxury watchmaker has ever created, with 20 complications.