Photographer Tonya Illman saw the 132-year-old bottle by chance while walking on a sand dune next to a beach near Wedge Island in January.
She said she picked up the bottle because she thought "it might look nice on display in my home".
Inside the gin bottle was a note written in German and dated 12 June 1886. Ms Illman's husband, Tim Illman, later helped translate the note.
The Western Australian Museum (WAM) confirmed the authenticity of the find, saying it believed the bottle was thrown from a German sailing ship attempting to find efficient shipping routes.
Between 1864 until 1933, German boats threw thousands bottles into the sea in attempts to track the currents of the ocean.
The messages in the bottles included the ship's coordinates, the date and the name of the ship.
The notes also asked the finder to write when and where the bottle had been found and return it to the German Naval Observatory in Hamburg or to the nearest German consulate.
Ross Anderson, from WAM, used the name written on the note, Paula, to confirm the age of the message.
He matched the name to maritime records of a German ship and found the handwriting was similar to a captain's entries in Paula's meteorological journal.
The previous world record for the oldest message in a bottle was 108 years, four months and 18 days, according to WAM.
Ms Illman said of the bottle's discovery: “I picked it up thinking it might look nice on display in my home.
"When I got back to the car, I handed it to my son’s girlfriend, Bree Del Borrello, to mind while I helped my husband get my son’s car out of the soft sand.”
Ms Del Borrow looked inside the bottle and saw what she thought was a cigarette, but discovered it was a damp, tightly-rolled note tied with string.
Ms Illman took the note home with her, where she dried it out.
The bottle and message will be on display at the Western Australian Maritime Museum in Fremantle for the next two years.
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