Bäckström’s father Anders is a known Swedish hockey player who played his whole hockey career for Brynäs, totaling 10 seasons for the club. Nicklas’ older brother Kristoffer is also a hockey player, but in the second tier of the Swedish league system with Hammarby.
Bäckström was a top prospect in the 2006 NHL Entry Draft and was selected fourth overall by the Washington Capitals. With that, he became the fourth-highest drafted Swede, after Mats Sundin (first), Daniel Sedin (second), and Henrik Sedin (third).
He played his first game with the Swedish national team on April 6, 2006, in a game against Norway. He won the World Championship when he represented Sweden in the 2006 World Championship. As of that tournament he is the youngest Swedish player ever in an Ice Hockey World Championship tournament. Bäckström played the last four games in the WC (roster spot held open for Daniel Alfredsson) and was directly appointed to the first line together with idol Henrik Zetterberg and Johan Franzén.
Upon his arrival to the NHL, Bäckström was solid but not spectacular as he made the transition to the smaller ice rinks of North America. However, after an injury to Nylander, Bäckström was promoted to the first line, where he flourished. Playing alongside Alexander Ovechkin, Bäckström set NHL and team records while helping Ovechkin win the Art Ross Trophy and the Maurice “Rocket” Richard Trophy.
Bäckström was the runner up to Chicago’s Patrick Kane for the Calder Trophy. Kane had 1,087 votes while Bäckström had 872 votes. The Blackhawks’ Jonathan Toews was third with 647. However, Bäckström was named to the All-Rookie Team along with Kane and Toews.
In his second NHL season, Bäckström would go on to lead both the Capitals and Swedish NHL players with 66 assists, and added 22 goals for 88 points, placing him within the top ten NHL scorers in the 2008–09 regular season. Bäckström would again prove to be a force in the playoffs, tallying 15 points in 14 games. Going into the 2009-10 NHL season, Bäckström has solidifed himself as the Washington Capitals number one center, pivoting Russian superstar Alexander Ovechkin.
Following the 2008–09 NHL playoffs, Bäckström was awarded the Viking Award for being the best Swedish-born player in the 2008–09 NHL season; he is only the second Capital to win this award, following behind Calle Johansson.
Bäckström’s entry-level contract expires after the 2009–10 NHL season, in which he will become a restricted free agent.
On December 27, 2009, it was announced that Bäckström would play for Team Sweden in the 2010 Winter Olympics.
Bäckström led Team Sweden in the 2010 Olympics with 6 points in 4 games before they were eliminated by Slovakia in the quarterfinals.