The 32-year-old, who has eight caps for Jamaica, was released by the Royals at the end of last season after five years with the club.
He captained the side during their spell in the Premier League two years ago and made 35 appearances in the Championship last term.
"It's been a long summer for me," McAnuff told the Orient website.
"I've had a few offers but have been waiting for the right fit and I believe I've found it here at Orient."
Former Reading midfielder Jobi McAnuff has joined League One side Leyton Orient on a two-year contract.