The trio will support new First Team Manager Mauricio Pochettino having previously worked with him at RCD Espanyol.
Saints' new members of staff will be assisted by Fran Alonso, who took up his position as First Team Technical Support Coach last autumn.
Andy Crosby, Dean Wilkins and Jim Stannard have been relieved of their coaching duties, and we thank them for their service during their respective periods with the Club.
Jesús Pérez Pérez – First Team Assistant Manager
Pérez will act as First Team Assistant Manager having previously worked as a technical coach under Pochettino during their time at RCD Espanyol.
The 41-year-old initially joined Espanyol as a first-team analyst in July 2010, before stepping up his involvement ahead of the 2010-11 campaign.
He made his name as a coach and assistant in his native Spain with Gimnàstic de Tarragona, CD Castellón, Real Murcia, Pontevedra CF, Rayo Vallecano and UD Almería.
Prior to joining Espanyol, he spent a season on the staff of Saudi Arabian side Al Ittihad having had an brief spell as a fitness coach with the Saudi Arabian national team in 2005.
Having now moved to Southampton, Jesús will assist Pochettino in day-to-day activities on the training ground and on matchdays.
First Team Coach – Miguel Angel D'Agostino
D'Agostino – also 41 – is appointed as First Team Coach after working with Pochettino at Espanyol in 2011 and 2012.
Born in Argentina, he began a playing career as a defender at local side Patronato de Paraná before moving to Newell's Old Boys in 1990.
D'Agostino played alongside Pochettino at the heart of the Newell's defence before the latter moved to Spain in 1994. Miguel then had a spell playing with Gimnasia y Esgrima de Jujuy before moving to Ecuadorian side LDU de Quito.
From there he moved to Chilean outfit C.D. Palestino before following in Pochettino's footsteps and heading to play in Spain with SD Compostela.
The pair both moved to France in 2000, with Pochettino joining Paris Saint-Germain and D'Agostino linking up with Chamois Niortais.
He went on to play for Canet en Rousillon and then joined Angoulême CFC as a player-coach before becoming assistant manager at Stade Brestois 29 between 2003 and 2007.
Next D'Agostino spent 2007-08 as assistant coach at Dubai CSC in the United Arab Emirates before returning to Brest as chief scout.
Following Pochettino's appointment at Espanyol, D'Agostino also did some scouting on behalf of his former teammate before moving to Spain on a permanent basis in 2011.
He now follows Mauricio to Southampton, and will work directly with the players as well as providing technical support to the manager.
First Team Goalkeeping Coach – Antoni Jiménez Sistachs
Former Spanish international goalkeeper and Olympic gold medallist Jiménez has been appointed as First Team Goalkeeping Coach.
Raised in the Spanish town of La Garriga, he began his playing career with lower-leaguers EC Granollers before joining Barcelona aged 18.
He spent a brief amount time playing for the Spanish giants' third team before moving on loan to make his professional debut with UE Figueres.
He was selected in Spain's squad for the 1992 Olympic Games in his home city of Barcelona, playing all six games as they won the gold medal for men's football.
After the games, he signed for Rayo Vallecano before following coach José Antonio Camacho to RCD Espanyol and fast becoming their first-choice goalkeeper.
Central defender Pochettino arrived at Espanyol a year after Jiménez's arrival, with the pair both forming a vital part of their starting team.
Jiménez won three senior caps for Spain, making his debut under his former Espanyol coach Camacho in a friendly against Italy in November 1998.
In 1999, after six years at Espanyol, Toni joined Atlético Madrid in 1999 before moving to Elche CF for a season in 2002.
He rounded off his playing career back at his beloved Espanyol, moving there in January 2003. He was reunited with Pochettino upon his return to Barcelona from France a year later, but decided to retire from playing at the end of the 2003-04 season.
After hanging up his gloves, Jiménez served as a director with Espanyol for just under two years before departing in March 2006.
He then had separate spells as assistant manager and goalkeeping coach at Girona FC either side of a role at his first club, EC Granollers.
Toni returned to Espanyol in June 2011 as Pochettino's number two, and now joins him in moving to Southampton.