The former Girona boss will serve as an assistant to both Tito Vilanova and Jordi Roura and will link up with the squad for the first time on July 15
The former Girona boss has signed a one-year contract with the Blaugrana, with the option of a further season.
"The full coaching team [for the 2013-14 season] will consist of Tito Vilanova as head coach; Jordi Roura as second coach, and ‘Rubi’ as their assistant," read a statement on Barcelona's official website.
"[He] will join Tito and the rest of the staff on July 15, the day that the first team is due to report back to start preparing for the new season."
Rubi last season led Girona into the Segunda Division play-offs, where their hopes of playing in La Liga for the first time were dashed by Almeria.