The Andalusians have secured their first signing of the season, with the Romania international penning a five-year deal at the club
The 24-year-old has signed a five-year deal with los Rojiblancos which will keep him at the Ramon Sanchez stadium until 2018.
The Romania international has become the club's first acquisition of the transfer window, but the club have stressed that he is not a replacement for Alvaro Negredo.
"He's not coming as a substitute for Negredo," deputy sporting director Monchi told SFC Radio.
"Today he is a Sevilla player. Negredo has nothing to do with the signing of Rusescu. He's a good striker with a good first touch. He moves well around the front of the attack.
"He's a player we have been following for some time."
The former Unirea forward finished up his domestic season with 21 goals - the highest in the league and has represented his country on two occasions.