He played college football for the Montana Grizzlies, and was selected by the Tennessee Titans in the seventh round of the 2010 NFL draft.

Mariani attended Havre High School where he was awarded 10 letters: three each in football and basketball and four in tennis.

Mariani, a walk-on at Montana in 2005 studying Business Marketing & Management, did not play football his first year.

He was a unanimous All-Big Sky pick at wide receiver, a second-team selection as a return specialist and was named a first-team All-American by the Associated Press.

[6] In a lesser known competition, Marc lost to Havre Blue Pony AA athlete John R. Velk in a five sport challenge before heading to the pros.

Mariani was selected by the Tennessee Titans in the seventh round of the 2010 NFL draft with the 222nd overall pick and later signed a four-year deal with the team.

[9] Mariani was selected to the 2011 Pro Bowl as a return specialist for the American Football Conference (AFC).

Mariani missed the entire 2012 season after he broke his leg on a first-quarter punt return in the third game of the preseason against the Arizona Cardinals.

[25] On August 1, 2018, he was announced as an assistant coach for the Lipscomb Academy Mustangs football team, working with wide receivers and returners.