His father, Anders, was a professional ice hockey player, who won a championship with the Brynäs and retired shortly after Bäckström was born.

"[3] The "ice barn" in Valbo where he developed his hockey skills as a young boy has been renamed to Nickback Arena.

He stated that "I'm not a fast skater, but when I was younger I always wanted to be a smart player and try to read my opponent.”[2] After turning 15, Bäckström began his junior career in the 2002–03 season, playing for Brynäs IF of the J20 SuperElit league.

Drawing comparisons to Peter Forsberg, he was noted primarily for his vision, passing and ability to maintain possession of the puck in traffic.

[6] For these reasons, he was expected to be a catalyst on the team's power play, and his defensive prowess and puck movement would make him an equally valuable asset when short-handed.

On 5 October 2007, he scored his first NHL point, an assist on a goal by fellow Swede Michael Nylander, against the Atlanta Thrashers.

At the conclusion of the 2009–10 regular season, Bäckström finished fourth in NHL scoring with 101 points, behind Henrik Sedin (112), Sidney Crosby (109) and teammate Alexander Ovechkin (109).

On 17 April 2012, Bäckström received a one-game suspension for a cross-check to the head of Boston Bruins forward Rich Peverley.

A pre-game ceremony was held for Bäckström for reaching 600 career assists on 7 November 2018, before the Capitals' game against the Pittsburgh Penguins.

[18][19] In a 4–1 win against the New York Islanders on 26 November, Bäckström recorded three assists and moved to the second place on the Capitals' all-time points list, passing Peter Bondra.

[21] On 11 December, Bäckström had his 12th career four-assist game in a 6–2 win over the Detroit Red Wings, tying him with Gilbert Perreault for eighth in NHL history.

[24] Bäckström scored his 1,000th career point on 9 March 2022 on an assist to T. J. Oshie against the Edmonton Oilers, becoming the second player in Capitals history to reach that threshold after Ovechkin.

Bäckström played the last four games in the World Championship (roster spot held open for Daniel Alfredsson) and was directly appointed to the first line together with idols Henrik Zetterberg and Johan Franzén.

[31] The International Ice Hockey Federation (IIHF) opposed the decision to stop Bäckström from playing in the final.

[34] However, in November 2014, the World Anti-Doping Agency (WADA) appealed the IOC decision to award Bäckström his silver medal.

[35] This appeal was resolved in January 2015 when Bäckström, the IOC, WADA and the IIHF agreed to a settlement in which he accepted a reprimand but was cleared of attempting to enhance his performance.

[36] Bäckström's father Anders is a Swedish hockey player who played his career for Brynäs IF, totaling ten seasons for the club.

Nicklas' mother Catrin Bäckström (born in Finland) played handball in the Swedish and Finnish Elite League in the late 1970s and early 1980s.