Jesus Perez, Miguel D'Agostino and Toni Jimenez, who previously worked with Pochettino at Espanyol, will join him at St Mary's.
The move sees Andy Crosby, Dean Wilkins and Jim Stannard leave the club, with the new trio supporting Fran Alonso, after he was named first team technical support coach last year.
Perez becomes Assistant Manager having previously worked as a technical coach under Pochettino in Spain.
D'Agostino has been confirmed as first team coach, while Jimenez becomes the goalkeeping coach.
"Southampton Football Club can confirm the appointment of Jesus Perez, Miguel D'Agostino and Toni Jimenez to the club's first team management staff," read a statement on the club's official website.
"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."