Orient will enter a side in the Final Third Development League for the 2014-15 season
The Final Third Development League, the oldest reserve league in England, will be running a division in the south of the country next season for the first time in its 103-year history.
The new structure will see a further eight teams play each other on a home and away basis, providing 14 fixtures, from 2014/15 onwards. It will operate in addition to the East and West divisions that include teams from the Midlands, as well as north Wales and north England, and see the League move to a national competition for the first time since it was formed in 1911.
Clubs from the south have been without competitive reserve team football since the Football Combination folded in 2012 and two of the clubs that played in that last season of competition - AFC Bournemouth and Luton Town - will be founder members of the new division.
They are joined by AFC Wimbledon, Cambridge United, Gillingham, Leyton Orient, Peterborough United and Portsmouth in the inaugural Final Third Development League Southern Division.
Ernest Barron, President of the Central League, commented: “When we partnered with Final Third Sports Media in January we announced our intention to expand the competition to a national format and we are delighted to have recruited eight new clubs to our membership.
"In addition to this, a handful of other clubs, who for variety of reasons weren't able to commit to join the division in time for next season, have expressed an interest in competing from 2015/16 so we anticipate the League will continue to increase in size.
“For the last five years, approximately two-thirds of all players who competed in the Final Third Development League have been under the age of 21 and we are confident the move to a national structure will give us a robust platform in which to help clubs develop young players further.
"The likes of Rickie Lambert, Joe Hart, Phil Jagielka, Leighton Baines and Ben Foster all played in the Central League a decade ago and this summer they will represent England at the World Cup. We hope many more will make their first competitive steps in men's football this way and follow in their footsteps."
The O's will host their reserve team games at the Matchroom Stadium.