The 25-year-old has signed a two-year contract with an option for a further year after turning down the offer of a new deal at Vale Park.
Huddersfield-born Griffith, who started his career at Doncaster, has spent the last four seasons at Vale and made a total of 47 appearances last season, scoring one goal.
He becomes Orient's second summer signing following the arrival last weekend of Gary Sawyer from Bristol Rovers.
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