Malachi Swaine, from Herne Bay, was trekking in West Blean Wood on the outskirts of the town when he found the bottle covered in moss next to a tree.
The 16-year-old Herne Bay High pupil said: “I am really into bushcraft and the outdoors, so I often go for treks in the local woods.
“On this particular walk, I saw something shining by a beech tree, so I went to have a look and found it was a dark glass bottle, almost completely covered by moss.
“It had Shepherd Neame and Co embossed on the side, and was in amazing condition, still with its screw top intact.”
Swaine took the bottle home, and his father Ian alerted Shepherd Neame to the find, resulting in an invitation to the Faversham-based brewery from archivist and historian John Owen.
Owen said: “The bottle is in absolutely remarkable condition, considering it is at least a century old.
“The brewery didn’t do any bottling before 1895, and it was called Shepherd Neame and Co until 1914, when it became Shepherd Neame Ltd, so it must have been made between those dates.
He added: “The oldest Shepherd Neame bottle in our collection at the brewery was only made in 1920, so this is a fantastic find.”
The bottle is now part of Shepherd Neame’s archive, and it will go on display in the brewery’s visitor centre later this year.
Swaine, who is in the Army Cadets, said: “I haven’t found anything this interesting before. I just thought it was an ordinary bottle, I never expected it to be so old. It is great to know it will now be on display at the brewery for years to come.”