Blues will compete in eight-team division next term
Pompey will field a reserve side in the newly-formed Final Third Development League Southern Division next season.
The Blues will be joined by AFC Wimbledon, Bournemouth, Cambridge, Gillingham, Leyton Orient, Luton and Peterborough in the eight-team set-up.
The sides will facing each other on a home and away basis, playing a total of 14 fixtures.
Pompey have not played in a reserve league since they were relegated from the Premier League in 2010.
The Final Third Development League – the oldest reserve league in England – are running a division in the south of the country for the first time in their 103-year history.
Last season Wigan won the West Division and Final Third Development Cup, while Hull claimed the East Division title and were crowned overall champions of the Final Third Development League by virtue of having the most points of all competing teams.
Ernest Barron, president of the Central League, said: “When we partnered with Final Third Sports Media in January, we announced our intention to expand the competition to a national format and we’re delighted to have recruited eight new clubs to our membership.
“In addition to this, a handful of other clubs, who for a 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.”