Levante have appointed Rubi as head coach following the sacking of Lucas Alcaraz.
Alcarez was dismissed after Sunday's 4-0 home defeat to Real Sociedad, a result that leaves Levante bottom of the table with six points from nine games.
He has been replaced by Rubi, who takes up a contract until the end of the season, which may be extended by a further two years.
Rubi served on Barcelona's staff during the 2013-14 campaign and will begin his reign with a trip to Levante's city rivals Valencia on Saturday.