Marioni made his debut under the last name Giménez for
Newell's Old Boys in 1995 before moving to
Estudiantes in 1997. After 2 seasons in Argentina, Marioni went to Portugal, joining
Sporting CP in 1998. In 1999, his father met his paternal grandfather, Luigi Marioni, for the first time. Shortly after, both him and Bruno adopted the elderly man's last name. After a single season in Portugal, he returned to Argentina to play for
Independiente. In 2000, he again played in Europe for
Villarreal CF, but shortly after, he returned to Independiente for the Torneo Clausura 2001. After the tournament, he joined
CD Tenerife, but once again returned to Independiente for the Apertura 2003, and then transferred to
Pumas UNAM in México. In his opening season there, he was the league's top scorer with 16 goals, along with fellow Argentine
Néstor Silvera. In 2005, Marioni was the
Copa Sudamericana's top scorer with 7 goals. He then played for
Toluca, and netted an Apertura-leading 11 goals, but in the January transfer window, he moved to
Boca Juniors. For Apertura 2007, he returns to Mexico for
Club Atlas. He played the
Interliga 2008 Tournament with
Club Atlas and qualified to
Copa Libertadores 2008. Marioni then joined
Pachuca on 15 June 2008. After playing only for a period of six months with
C.F. Pachuca, he returned to Club Atlas citing his family's needs before his economic earnings. In June 2009, Marioni agreed to join
Estudiantes Tecos. On 12 November 2009, Marioni held a press conference to announce his retirement from professional football. ==Honours==