David Krejčí was the Boston Bruins‘ first pick in the second round of the 2004 NHL Entry Draft (63rd overall) He was drafted out ofCzech junior leagues, having played for HC Kladno. Following his selection, he moved to North America to play major junior hockeyin the Quebec Major Junior Hockey League (QMJHL) for the Gatineau Olympiques for two seasons.
Krejčí turned pro in 2006–07, playing for the Bruins’ American Hockey League (AHL) affiliate, the Providence Bruins. He played in his first NHL game on January 30, 2007 in a 7–1 loss against the Buffalo Sabres, but suffered a concussion from Buffalo’s Adam Mairduring his third shift. He recorded just 2:07 minutes of ice time. Krejčí played increasingly with Boston the following season, appearing in 56 NHL games to go with 25 games in Providence. On February 19, 2008, Krejčí was involved in a shootout tie-breaker round, in a Bruins road game against the Carolina Hurricanes, and scored to help the Bruins take the shootout 2–1. Krejčí’s shootout tally would not, however, register as his first NHL goal as shootout goals do not count towards a player’s statistical totals. Krejčí scored his first official NHL goal a week later, on February 26, against Martin Gerber of the Ottawa Senators, as the second Bruins goal in a 4–0 home-ice shutout. He finished his rookie NHL season with 6 goals and 27 points.
In 2008–09, Krejčí scored his first NHL hat-trick on December 18, 2008 against the Toronto Maple Leafs. He registered his first two goals against starter Vesa Toskala and his third against Curtis Joseph in an 8–5 Bruins win. Before a game on April 2, 2009, Krejčí was named the winner of the Boston Bruins’ 2009 Seventh Player Award. The award is given annually to the player who “goes beyond the call of duty and exceeds all expectations” throughout the course of the season. During the game, Krejčí assisted on a goal by Milan Lucic, the 2008 winner of the Seventh Player Award, in a 2–1 home ice victory over the Ottawa Senators. Krejčí is known for his puck control and his playmaking ability from the pivot position for the Bruins. He completed his second NHL season with 73 points in 82 games to go with a league-high +37 plus-minus rating, earning him the NHL Plus-Minus Award.
At the beginning of November 2009, Krejčí was noticeably ill, and this was confirmed on November 5, 2009 with a diagnosis of infection with the H1N1 virus, which sidelined Krejčí for a period of time.
On May 5, 2010 Krejčí dislocated his wrist less than five minutes into game 3 when he was leveled at the Bruins’ blue line by Flyers center Mike Richards. Surgery was needed and was performed following the game at Union Memorial Hospital in Baltimore, and Krejčí missed the remainder of the 2010 Playoffs.
On May 25, 2011 Krejčí recorded his second NHL career hat trick against the Tampa Bay Lightning during Game 6 of the Eastern Conference Finals during the Stanley Cup Playoffs. He is the first Bruin to record a playoff hat trick since Cam Neely, two decades prior.
On June 15, 2011 Krejčí and the Bruins won the teams first Stanley Cup in 39 years, beating the Vancouver Canucks 4-0 in Game 7. Krejčí finished the 2011 playoffs with a league-leading 12 goals, 23 points and 4 game-winning goals.
After the Bruins’ 2007–08 season ended, Krejčí was named to the Czech national team on April 26, 2008 for the 2008 IIHF World Championships. He was named to the Czech national team for the 2010 Winter Olympics, playing center on a line with wingers Tomáš Fleischmann and Martin Erat to open the Games.