Russell Slade made left back Gary Sawyer his first summer signing of 2012 when he captured the Enfield-born defender on a two-year contract.
Sawyer made 42 appearances for Orient in the 2012-13 season and scored his first goal for the club against MK Dons in April 2013.
The defender saw his playing time reduced last season and made 28 appearances for the O’s before signing a new one-year deal in May 2014.
The ex-Plymouth man spent the previous two years at the Memorial Stadium, making 61 League appearances for the Pirates after previously enjoying a brief loan spell across Bristol at Bristol City.
He began his career at Plymouth after moving down to the south west as a youngster, breaking through after spending two seasons on loan at Exeter City earlier in his career.
Gary went on to play 95 games at Championship level for the Pilgrims and has eight career League goals to his name.