That summer, Kris was drafted in the 3rd round (62nd overall) in the 2005 NHL Entry Draft by the Pittsburgh Penguins. The next season, a 68-point effort in just 60 games earned him QMJHL First Team All-Star honours.
Making the Penguins out of training camp, Kris made his NHL debut in the 2006–07 season.
He scored his first NHL goal in his third game against [[Henrik Lundqvist]] of the New York Rangers in a 6-5 win, however, after two goals in seven games, Kris was scratched twice and then returned to Val-d'Or for further development.
Playing in his third season with Val-d'Or, Kris led the Foreurs to the 2007 QMJHL Finals with 31 points in the post-season, only to be swept by Lewiston in four games. Upon the Foreurs' elimination, he was assigned to the Wilkes-Barre/Scranton Penguins of the American Hockey League (AHL), who was in the second round of the Calder Cup playoffs and recorded an assist in his only game.▼
Playing in his third season with Val-d'Or, Kris led the Foreurs to the 2007 QMJHL Finals with 31 points in the post-season, only to be swept by Lewiston in four games. Upon the Foreurs' elimination, he was assigned to the Wilkes-Barre/Scranton Penguins of the American Hockey League (AHL), who was in the second round of the Calder Cup playoffs and recorded an assist in his only game.
At the season's end, Kris was the recipient of three major QMJHL awards. In addition to receiving the Emile Bouchard Trophy, as the best defenceman and the Paul Dumont Trophy, as the best personality, he also received the Kevin Lowe Trophy, as the best defensive defenceman, indicative of Kris's abilities on both ends of the ice.
After beginning the 2007–08 season in Wilkes-Barre/Scranton, Kris was quickly recalled by Pittsburgh after recording 7 points in 10 games in the minors.
He excelled in his rookie season with Pittsburgh and was invited to the 2008 NHL YoungStars Game during All-Star weekend along with teammate [[Tyler Kennedy]].
Kris completed the season with 17 points in 63 games, sixth among rookie defencemen. Making his NHL playoff debut, he helped the Penguins to the 2008 Stanley Cup Finals where they were defeated in six games by the Detroit Red Wings.
The following season, Kris recorded a career-low 3 goals to go with 24 assists. Late in the regular season, on March 30, 2010, he signed a four-year contract extension through to the 2013–14 season, worth an annual $3.5 million.
Going into the 2010 Stanley Cup playoffs as defending champions, the Penguins were eliminated in the second round by the Montreal Canadiens.
Kris surpassed his regular season goals total with five tallies in 13 post-season games along with 2 assists for 7 points.
With the departure of the Penguins' top defenceman Sergei Gonchar the following summer, Kris assumed a larger role with the club in 2010–11. Enjoying a career year, he was voted in as a starter for the [[2011 NHL All-Star Game]] in Raleigh, North Carolina.
On January 23, 2012, Kris made the NHL 2012 All-Star roster as an injury replacement for [[Dustin Byfuglien]] joining teammates Evgeni Malkin and [[James Neal]].
In their first round loss to the Stanley Cup playoffs against the Philadelphia Flyers,
Kris scored one goal and had two assists while earning a game misconduct in Game 3 for fighting [[Kimmo Timonen]].
On July 2, 2013, Kris signed an 8-year contract with Pittsburgh valued at $58 million that goes into effect in the 2014-2015 season.