[1] He played as a forward for several Canadian and American lower division clubs, namely Montreal Supra, Buffalo Blizzard, Rochester Raging Rhinos, and Toronto Thunderhawks.

In 1997, Biello helped the Impact win the regular-season title by scoring 8 goals and recording 10 assists.

As the Impact was no longer playing indoor soccer, Biello spent the winter of 2000–01 with the Toronto Thunderhawks in the NPSL.

In 2004, Biello led the Impact to win the club's second league championship, beating the Seattle Sounders.

Biello also was a finalist for League MVP honors, losing to Jason Jordan, and for the fourth time in his career he was awarded the Giuseppe-Saputo Trophy.

Mauro also helped the Impact capture the Voyageurs Cup for a fourth straight year.

On January 5, 2009, the Montreal Impact announced that Biello and veteran midfielder Patrick Leduc had both accepted contract extensions for the 2009 season.

[5] During the 2009 USL season Biello contributed by helping the Impact clinch a playoff spot under new head coach Marc Dos Santos.

[9] Biello guided the team to the Eastern Conference semi-finals where they were eliminated by Columbus Crew.

[15] On August 28, 2023, John Herdman resigned from the men's national team in order to join Toronto FC as their head coach.

Montreal Impact Rochester Raging Rhinos Biello's sons are also soccer players; Gabriele played in the academy of Montreal Impact and is currently in the roster of the Soccer team of Dawson College (Blues); and Alessandro plays for HFX Wanderers.