Brännström played junior hockey with Swedish team HV71. In 2013–14, he debuted at the under-16 level, playing twenty-three games in the J16 SM. The following season Brännström moved on to HV71's J20 SuperElit. In 2015–16, Brännström made his Swedish Hockey League debut.[1][2][3]
He was drafted 15th overall in the 2017 NHL entry draft by the Vegas Golden Knights[4] and agreed to a three-year, entry-level contract with the Knights on 16 July 2017.[5] He played the 2017–18 season with the HV71 organization. Brännström earned his first NHL recall on 5 May 2018 to help the Golden Knights during their 2018 Stanley Cup playoffs run, but did not appear in any games.[6]
Brännström attended the Golden Knights 2018 training camp but was reassigned to the American Hockey League (AHL) on 27 September 2018.[7] During the 2018–19 season, Brännström was selected to participate in the 2019 AHL All-Star Game.[8]
Brännström with the Ottawa Senators in 2022
On 25 February 2019, Brännström was traded to the Ottawa Senators as part of a package to acquire forwards Mark Stone and Tobias Lindberg. In addition to Brännström, Ottawa acquired Oscar Lindberg and a 2020 second round draft pick in the deal.[9] After the trade, Brännström was assigned to Ottawa's AHL team, the Belleville Senators.[10] He was recalled from the AHL and made his NHL debut with Ottawa on 14 March 2019 in a game against the St. Louis Blues.[11] He was then returned to Belleville following the game.[12] He opened the 2019–20 season with the Senators, but struggled at the NHL level and was sent down to Belleville on 5 December 2019.[13] He was recalled only 11 days later on 16 December after playing in four games with Belleville, collecting one goal and four points.[14] Brännström was returned to Belleville on 3 January 2020.[15] At the end of February, he suffered a wrist injury with Belleville that caused him to miss some games.[16]
On 5 October 2020, Brännström was loaned to the SCL Tigers of the National League (NL) for the start of the 2020–21 season.[17] He made his NL debut with the Tigers on 15 October 2020 in a 8–1 away loss to Genève-Servette HC. On 21 November 2020, in his eighth game with the Tigers, Brännström was punched in the face by EHC Biel's Damien Brunner during a line change in the third period. Brännström was not injured on the play and Brunner immediately received a game misconduct.[18] On 11 December 2020, Brännström left the Tigers after having appeared in 10 games (8 points) to return to Ottawa for the start of training camp.[19] The 2020–21 NHL season was abbreviated due to the COVID-19 pandemic and the season did not begin until January 2021.[20] Brännström did not make the Ottawa Senators out of training camp and was assigned to Belleville on 13 January.[21] He was recalled on 4 February 2021 and placed on the taxi squad. He played his first game of the season versus the Montreal Canadiens, playing on the second power play unit.[22][23] He scored his first NHL goal on 24 February 2021 versus the Montreal Canadiens.[24] On 5 May 2021, he had three assists in a 5–1 win over Montreal, marking his first multi-point game.[25] Brännström finished the season with two goals and thirteen points in thirty games with the Senators.[26]
Brännström began the 2021–22 season in Belleville. He was recalled on 7 November 2021 after Nick Holden was placed in COVID-19 protocol.[26] On 13 November, he broke his hand blocking a shot in a game versus the Los Angeles Kings.[27] He returned to the lineup on 1 January 2022.[28] He finished the season with 14 points in 53 games with Ottawa.[29] On 5 September 2022, Brännström signed a one year, $900,000 contract extension with the Ottawa Senators.[30] During the 2022–23 season Brännström's play improved as he was often called on to replace injured defenceman after a number of them, including regulars Thomas Chabot and Jakob Chychrun, were affected.[31] He finished the season with two goals and 18 points in 74 games.
A restricted free agent at the end of the season, Brännström signed a one-year contract extension with the Senators on 1 July 2023.[32] In the following 2023–24 season, Brännström appeared in a career best 76 regular season games, making his 200th appearance on 18 November 2023. With the Senators missing the post-season he finished the season by notching career marks with 3 goals and 17 assists for 20 points.
As a pending restricted free agent, Brännström was released by the Senators after he was not tendered a qualifying offer, becoming an unrestricted free agent.[33] Ending his five-year tenure with the Senators, Brännström was soon signed as a free agent to a one-year, $900,000 contract with the Colorado Avalanche on 2 July 2024.[34] He attended the Avalanche's 2024 training camp and on the last day was traded to the Vancouver Canucks for defenceman Tucker Poolman and a fourth-round draft pick in 2025. Vancouver immediately placed him on waivers and after going unclaimed, assigned Brännström to their AHL affiliate, the Abbotsford Canucks.[35][36] He was recalled by Vancouver on 16 October after teammate Derek Forbort left the Canucks for personal reasons.[37]
Personal life
Brännström's older brother Isac, is also a professional hockey player, currently with Luleå HF.