Sam began his football career at Charlton Athletic but spent a portion of his childhood living in Senegal where he attended Dakar Academy.

When Sam's family returned to London in 1998, he was offered trials at both Wimbledon and Arsenal, but instead re-joined Charlton on Academy terms.

His and Osei Sankofa's impressive form for the youth side resulted in a call up to the first team squad against Arsenal, but it was two years before he made his debut for Charlton against Crystal Palace on the final day of the 2004–05 season.

Sam and Charlton narrowly missed out on promotion back to the Premier League, after poor end of season form saw them drop out of the play-off positions to 11th place.

He narrowly missed out on promotion the following season, when Charlton reached the League One playoff semi-finals, but ended up losing against Swindon Town.

Sam was not offered a new contract by Charlton after they failed to gain an immediate return to the Championship, as they could not afford his wages, which had been set during their final Premier League season in 2006–07 under Iain Dowie.

Sam signed a two-year deal with his hometown club Leeds United on 9 July 2010 on a free transfer from Charlton Athletic.

[4] After being an ever-present for Leeds, Sam sustained a minor foot injury, was dropped for the game against Swansea City on 11 September and replaced in the starting lineup by Max Gradel.

[11] Sam again made an impressive impact as a substitute against Crystal Palace helping Leeds earn a 2–1 win.

[13] Sam was involved in some controversy against Hull City, when he accidentally collided with Liam Rosenior who suffered a neck injury.

[16] After an injury hit 2010–11 season, Sam revealed he had been doing extra work in the gym over the summer period to help strengthen his leg.

[17] After providing several assists in the pre season matches, Sam topped off a fine pre-season with a goal against Newcastle United.

[26] Sam appeared in five league matches for the club showing impressive form before being sidelined for the rest of the season with a knee injury.

[27] On the final day of the season Sam scored New York's third goal in a 5–2 victory over Chicago Fire which gave the club its first title the 2013 Supporters' Shield.

[33] On 7 October, Sam scored his tenth league goal of the season for New York to help the Red Bulls to a 2–1 victory over Montreal Impact.

[38] Despite leading the team in key passes and assists,[39] United declined Sam's contract option at the end of the 2017 season.

[45][46] Following the end of the NPSL season, Miami joined the newly formed third division National Independent Soccer Association.