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 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 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.