The Museum of London team discovered the cache buried in an empty human grave near St. Martin-in-the-Fields church, north of Trafalgar Square.
"Our excavations demonstrate the position as a significant and important place at an earlier date than we thought," Alison Telfer, the senior archaeologist in charge of the dig, told The Independent.
The excavation also unearthed at least one grave archaeologists said was pre-Anglo-Saxon, possibly dating to the very late Roman or immediate post-Roman period.
The finds are likely to provide more information on the very early stages of introducing Christian ideas into the Anglo-Saxon world 1,400 years ago.
Archaeologists said they found a gold pendant inlaid with blue-green glass, glass beads and fragments of silver, and two pieces of amethyst. Judging from nearby graves in the cemetery, they estimate the grave and its treasures could date from 590 to 610.
The empty grave may be part of a previously unknown ancient cemetery where the team said it also found 24 other graves.