The Flames assigned Giordano to their American Hockey League (AHL) affiliate, the Lowell Lock Monsters, for the 2004–05 season where he scored 6 goals and added 10 assists in 66 games.
 He remained in the AHL for much of the 2005–06 season, transferring to Calgary's new affiliate, the Omaha Ak-Sar-Ben Knights.
 Giordano led the Knights in scoring, recording 16 goals and 58 points in 73 games.
Additionally, he was second among defencemen in the AHL in goal scoring and fourth in points.
The Flames recalled him to Calgary at mid-season, and he made his NHL debut on January 30, 2006, against the St. Louis Blues.
Giordano appeared in seven games with the Flames, and recorded his first NHL point with an assist on April 8, 2006, against the Vancouver Canucks.
In the 2006–07 season, Giordano played only five games in Omaha as he spent the majority of the campaign in Calgary.
In 48 games with the Flames, he recorded 7 goals and 15 points.
 Giordano scored his first two NHL goals on October 14, 2006, against the Toronto Maple Leafs.

Unable to come to terms on a new contract with the Flames prior to the 2007–08 season, Giordano left the NHL to sign with HC Dynamo Moscow of the Russian Super League.
According to Playfair, Giordano did not sign in Russia over money.
Instead, he left due to the fact that he felt he had proven what he could do in the AHL and, lacking a guarantee that he would be in the NHL, sought a higher calibre league in which to play.
He scored 4 goals and 13 points in 50 games with Dynamo, and played with the winning Canadian team at the 2007 Spengler Cup.
The Canadian national team named him an alternate at the 2008 IIHF World Championship in case of injury to a roster player, however he never appeared in a game.
 Though he feared his decision to leave for Russia would damage his relationship with the Flames, Giordano and the team came to terms on a three-year contract that brought him back to Calgary for the 2008–09 NHL season.

Giordano appeared in 58 games for the Flames and scored 19 points before a shoulder injury ended his season.
He required surgery to repair the damage suffered in a game against the Minnesota Wild.
He recovered in time to begin the 2009–10 season, but several new additions to Calgary's defensive corps left him concerned about his position with the team.
Instead, he solidified his place on the roster with a career year; Giordano set personal highs in goals (11), points (30) and was +17 for the Flames.
The Hockey News named him one of the most underrated players in the league, and he was invited to join Team Canada at the 2010 IIHF World Championship.
Giordano led the team's defencemen with three goals in the tournament and added an assist in seven games.

Despite having the option to become an unrestricted free agent following the 2010–11 season, Giordano opted to remain in Calgary and signed a five-year, $20 million contract extension with the Flames on October 29, 2010.
He led the team's defencemen in scoring and set another career high with 43 points in 82 games.
Giordano missed several weeks of the 2011–12 season after suffering a torn hamstring.
The injury caused Giordano, who was named an alternate captain prior to the season's start, to miss 21 games.
He finished with 27 points in 61 games, then scored 15 points in 47 games in the lockout-shortened 2012–13 season.

Giordano was named the 19th captain in Flames history on September 20, 2013, as he succeeded Jarome Iginla, who was traded late in the 2012–13 season.
Giordano was praised by his teammates and coaches staff for both his long tenure with the franchise and for his playing style: Giordano played in all situations for the Flames, was one of the hardest workers on the team and was willing to sacrifice himself to block a shot or defend his teammates.
Head coach Bob Hartley praised Giordano's influence on his teammates as the rebuilding Flames team established an identity as a squad which was noted across the league for its work ethic.

A blocked shot injured Giordano early in the 2013–14 season as he suffered a broken ankle in late
The Flames assigned Giordano to their American Hockey League (AHL) affiliate, the Lowell Lock Monsters, for the 2004–05 season where he scored 6 goals and added 10 assists in 66 games.  He remained in the AHL for much of the 2005–06 season, transferring to Calgary's new affiliate, the Omaha Ak-Sar-Ben Knights.  Giordano led the Knights in scoring, recording 16 goals and 58 points in 73 games. Additionally, he was second among defencemen in the AHL in goal scoring and fourth in points. The Flames recalled him to Calgary at mid-season, and he made his NHL debut on January 30, 2006, against the St. Louis Blues. Giordano appeared in seven games with the Flames, and recorded his first NHL point with an assist on April 8, 2006, against the Vancouver Canucks. In the 2006–07 season, Giordano played only five games in Omaha as he spent the majority of the campaign in Calgary. In 48 games with the Flames, he recorded 7 goals and 15 points.  Giordano scored his first two NHL goals on October 14, 2006, against the Toronto Maple Leafs.
Unable to come to terms on a new contract with the Flames prior to the 2007–08 season, Giordano left the NHL to sign with HC Dynamo Moscow of the Russian Super League. According to Playfair, Giordano did not sign in Russia over money. Instead, he left due to the fact that he felt he had proven what he could do in the AHL and, lacking a guarantee that he would be in the NHL, sought a higher calibre league in which to play. He scored 4 goals and 13 points in 50 games with Dynamo, and played with the winning Canadian team at the 2007 Spengler Cup. The Canadian national team named him an alternate at the 2008 IIHF World Championship in case of injury to a roster player, however he never appeared in a game.  Though he feared his decision to leave for Russia would damage his relationship with the Flames, Giordano and the team came to terms on a three-year contract that brought him back to Calgary for the 2008–09 NHL season.
Giordano appeared in 58 games for the Flames and scored 19 points before a shoulder injury ended his season. He required surgery to repair the damage suffered in a game against the Minnesota Wild. He recovered in time to begin the 2009–10 season, but several new additions to Calgary's defensive corps left him concerned about his position with the team. Instead, he solidified his place on the roster with a career year; Giordano set personal highs in goals (11), points (30) and was +17 for the Flames. The Hockey News named him one of the most underrated players in the league, and he was invited to join Team Canada at the 2010 IIHF World Championship. Giordano led the team's defencemen with three goals in the tournament and added an assist in seven games.
Despite having the option to become an unrestricted free agent following the 2010–11 season, Giordano opted to remain in Calgary and signed a five-year, $20 million contract extension with the Flames on October 29, 2010. He led the team's defencemen in scoring and set another career high with 43 points in 82 games. Giordano missed several weeks of the 2011–12 season after suffering a torn hamstring. The injury caused Giordano, who was named an alternate captain prior to the season's start, to miss 21 games. He finished with 27 points in 61 games, then scored 15 points in 47 games in the lockout-shortened 2012–13 season.
Giordano was named the 19th captain in Flames history on September 20, 2013, as he succeeded Jarome Iginla, who was traded late in the 2012–13 season. Giordano was praised by his teammates and coaches staff for both his long tenure with the franchise and for his playing style: Giordano played in all situations for the Flames, was one of the hardest workers on the team and was willing to sacrifice himself to block a shot or defend his teammates. Head coach Bob Hartley praised Giordano's influence on his teammates as the rebuilding Flames team established an identity as a squad which was noted across the league for its work ethic.
A blocked shot injured Giordano early in the 2013–14 season as he suffered a broken ankle in late
Mark Giordano