Preah Sihanouk Police Chief Maj. Gen. Chuon Narin said that Bambridge’s remains were found in the Gulf of Thailand just northwest of Koh Rong, where she was last seen on the night of Oct. 23 at a beach party.
Her body was close to the maritime border of Thailand.
Bambridge’s family initially thought that she may have gotten lost in the dense jungle, but after her bag and cellphone where found on a rock near the ocean, officials in Cambodia turned their attention to a possible drowning.
More than 150 people, including divers and navy personnel, searched for several days with no sign of the young traveler.
Thursday’s news was confirmed by Bambridge’s brother, Harry, in a message posted to his Facebook page.
“I’m so sorry to all her friends and family there's nothing more I wanted then to bring her back alive," he wrote. "And I'm sorry to you Amelia Bambridge the round is on me when we meet again in heaven."
Bambridge began a trip to Asia on Sept. 27, when she arrived in Vietnam. Her father, Phil, lived in the country teaching English and told local media that he had cautioned her about being safe before she set off.
Fox News' Stephen Sorace and The Associated Press contributed to this report.