Christiansen was born on 20 February 1994, in Bornholm, Denmark, where his journey into badminton began at a young age in the town of Allinge. His introduction to the sport was quite serendipitous; he started playing after his schoolteacher encouraged him to attend badminton practice.^[1] Christiansen's talent quickly became evident, leading him to compete at the international level as a teenager, including a notable debut at the 2011 Scottish International. His early career reached a significant milestone in 2013 when he moved to Copenhagen to join the Danish national team, marking his transition into the professional circuit where he would eventually become a key figure in both men's and mixed doubles.^[3]

In 2017, Christiansen and Daugaard secured a bronze medal in the men's doubles at the European Championships and reached a career-high ranking of No. 19 in that category.^[4] However, his profile rose significantly in late 2017 when he paired with the legendary Christinna Pedersen. This duo quickly became a global powerhouse, reaching back-to-back finals at the China and Hong Kong Open.^[5][6] In 2018, the pair captured the India Open title and earned a silver medal at the European Championships in Huelva, Spain.^[7][8] Their consistent performance at elite tournaments, including a runner-up finish at the Korea Open,^[9] propelled Christiansen to a career-best world ranking of No. 4 in October 2018. Additionally, he helped the national team secure a bronze medal at the 2018 Thomas Cup in Bangkok.

Following Pedersen's retirement from international play in early 2019, Christiansen began his current partnership with Alexandra Bøje.^[10] Making their debut at the Canada Open in July, they reached the podium finishing as runners-up in the Hungarian International in November, and then claimed two titles in the Irish and Scottish Open.^[11][12]

Christiansen helping Denmark secure gold at the 2021 European Mixed Team Championships and contributing to back-to-back bronze medals at the 2020 and 2022 Thomas Cup finals. On the individual circuit, Christiansen and Bøje won the bronze medal at the 2021 European Championships.^[13] They also captured titles at the 2020 SaarLorLux Open and the 2021 Orléans Masters,^[14][15] reached the finals of the 2021 Swiss and French Open,^[16][17] and made his Olympic debut at the Tokyo 2020 Games.^[2] His consistency against the world's best culminated in a career-high world ranking of No. 8 in October 2022.

In 2023, Christiansen and Bøje were in top form, capturing titles at the Spain Masters and the Singapore Open,^[18][19] and securing a bronze medal at the European Games in Poland.^[20] This momentum continued into early 2024 as they reached the final of the European Championships in April, earning a silver medal,^[21] and were runners-up at the Canada Open in July.^[22]

However, just days before the 2024 Paris Olympics, for which they had qualified, Christiansen announced his withdrawal from the Games. The decision followed a series of three unintentional administrative errors in reporting his "whereabouts" to Anti-Doping Denmark over a 12-month period. To avoid disrupting the Danish Olympic team with the pending investigation, Christiansen chose to step down, which eventually resulted in a one-year suspension that lasted until July 2025.^[23]

The year 2025 marked a triumphant return to the professional circuit for Christiansen after completing a one-year suspension related to anti-doping whereabouts reporting.^[24] Reunited with his longtime partner, Alexandra Bøje, the pair made an immediate impact by winning the Macau Open in their very first tournament back in July.^[25] They carried this momentum into the BWF World Championships in Paris, where they pulled off a massive upset against the world No. 1 seeds, Feng Yanzhe and Huang Dongping.^[24] Throughout the fall, Christiansen and Bøje continued their high-level play, securing another title at the Hylo Open,^[26] and an additional victory at the Indonesia Masters Super 100.^[27] By the end of 2025, Christiansen had successfully rehabilitated his world ranking from outside the top 150 back toward the elite tier.^[28]

The pair has maintained high-level consistency in 2026, notably reaching the finals of major tournaments such as the India Open and the Indonesia Masters in January.^[29][30] In March, they secured a runner-up finish at the Orléans Masters in France.^[31] Two months later, they went on to win their first title of the year at the Thailand Open, beating Chinese pair of Zhu Yijun and Li Qian.^[32] This pair then continued their winning streak by grabbing the Singapore Open title by beating the young Japanese pair of Yuichi Shimogami and Sayaka Hobara in three games.^[33] The next week, Christiansen and Bøje recorded their biggest win of their career by securing the Indonesia Open title, beating Chinese pair of Cheng Xing and Zhang Chi in the final.^[34]

Mixed doubles

Year	Venue	Partner	Opponent	Score	Result	Ref
2023	Arena Jaskółka, Tarnów, Poland	Alexandra Bøje	Robin Tabeling Selena Piek	14–21, 13–21	Bronze	[20][35]

Men's doubles

Year	Venue	Partner	Opponent	Score	Result	Ref
2017	Sydbank Arena, Kolding, Denmark	David Daugaard	Mathias Boe Carsten Mogensen	10–21, 15–21	Bronze	[4]

Mixed doubles

Year	Venue	Partner	Opponent	Score	Result	Ref
2016	Vendéspace, La Roche-sur-Yon, France	Lena Grebak	Niclas Nøhr Sara Thygesen	21–15, 18–21, 17–21	Bronze
2018	Palacio de los Deportes Carolina Marín, Huelva, Spain	Christinna Pedersen	Chris Adcock Gabby Adcock	18–21, 21–17, 18–21	Silver	[8]
2021	Palace of Sports, Kyiv, Ukraine	Alexandra Bøje	Marcus Ellis Lauren Smith	17–21, 19–21	Bronze	[13][36]
2024	Saarlandhalle, Saarbrücken, Germany	Alexandra Bøje	Thom Gicquel Delphine Delrue	16–21, 15–21	Silver	[21]
2026	Palacio de los Deportes Carolina Marín, Huelva, Spain	Alexandra Bøje	Callum Hemming Estelle van Leeuwen	21–19, 21–14	Gold

Boys' doubles

Year	Venue	Partner	Opponent	Score	Result	Ref
2013	Aski Sports Hall, Ankara, Turkey	David Daugaard	Kasper Antonsen Oliver Babic	17–21, 23–25	Silver

The BWF World Tour, which was announced on 19 March 2017 and implemented in 2018,^[37] is a series of elite badminton tournaments sanctioned by the Badminton World Federation (BWF). The BWF World Tour is divided into levels of World Tour Finals, Super 1000, Super 750, Super 500, Super 300, and the BWF Tour Super 100.^[38]

Mixed doubles

Year	Tournament	Partner	Level	Opponent	Score	Result	Ref
2018	India Open	Super 500	Christinna Pedersen	Praveen Jordan Melati Daeva Oktavianti	21–14, 21–15	Winner	[7]
2018	Korea Open	Super 500	Christinna Pedersen	He Jiting Du Yue	18–21, 16–21	Runner-up	[9]
2020	SaarLorLux Open	Super 100	Alexandra Bøje	Mark Lamsfuß Isabel Herttrich	21–15, 19–21, 21–11	Winner	[14]
2021	Swiss Open	Super 300	Alexandra Bøje	Thom Gicquel Delphine Delrue	19–21, 19–21	Runner-up	[16]
2021	Orléans Masters	Super 100	Alexandra Bøje	Niclas Nøhr Amalie Magelund	21–13, 21–17	Winner	[15]
2021	French Open	Super 750	Alexandra Bøje	Yuta Watanabe Arisa Higashino	8–21, 17–21	Runner-up	[17]
2023	Spain Masters	Super 300	Alexandra Bøje	Praveen Jordan Melati Daeva Oktavianti	22–20, 21–18	Winner	[18]
2023	Singapore Open	Super 750	Alexandra Bøje	Yuta Watanabe Arisa Higashino	21–14, 20–22, 21–16	Winner	[19]
2024	Canada Open	Super 500	Alexandra Bøje	Jesper Toft Amalie Magelund	21–9, 22–24, 12–21	Runner-up	[22]
2025	Macau Open	Super 300	Alexandra Bøje	Jimmy Wong Lai Pei Jing	21–13, 21–16	Winner	[25]
2025 (I)	Indonesia Masters Super 100	Super 100	Alexandra Bøje	Jimmy Wong Lai Pei Jing	13–21, 23–21, 21–14	Winner	[27]
2025	Hylo Open	Super 500	Alexandra Bøje	Thom Gicquel Delphine Delrue	23–21, 21–15	Winner	[26]
2026	India Open	Super 750	Alexandra Bøje	Dechapol Puavaranukroh Supissara Paewsampran	21–19, 23–25, 18–21	Runner-up	[29]
2026	Indonesia Masters	Super 500	Alexandra Bøje	Chen Tang Jie Toh Ee Wei	21–15, 17–21, 11–21	Runner-up	[30]
2026	Orléans Masters	Super 300	Alexandra Bøje	Thom Gicquel Delphine Delrue	19–21, 13–21	Runner-up	[31]
2026	Thailand Open	Super 500	Alexandra Bøje	Zhu Yijun Li Qian	21–17, 21–15	Winner	[32]
2026	Singapore Open	Super 750	Alexandra Bøje	Yuichi Shimogami Sayaka Hobara	17–21, 21–12, 21–12	Winner	[33]
2026	Indonesia Open	Super 1000	Alexandra Bøje	Cheng Xing Zhang Chi	21–19, 23–21	Winner	[34]

The BWF Superseries, which was launched on 14 December 2006 and implemented in 2007,^[39] was a series of elite badminton tournaments, sanctioned by the Badminton World Federation (BWF). BWF Superseries levels were Superseries and Superseries Premier. A season of Superseries consisted of twelve tournaments around the world that had been introduced since 2011.^[40] Successful players were invited to the Superseries Finals, which were held at the end of each year.

Mixed doubles

Year	Tournament	Partner	Opponent	Score	Result	Ref
2017	China Open	Christinna Pedersen	Zheng Siwei Huang Yaqiong	15–21, 11–21	Runner-up	[5]
2017	Hong Kong Open	Christinna Pedersen	Zheng Siwei Huang Yaqiong	15–21, 13–21	Runner-up	[6]

  BWF Superseries Finals tournament

  BWF Superseries Premier tournament

  BWF Superseries tournament

The BWF Grand Prix had two levels, the Grand Prix and Grand Prix Gold. It was a series of badminton tournaments sanctioned by the Badminton World Federation (BWF) and played between 2007 and 2017.

Men's doubles

Year	Tournament	Partner	Opponent	Score	Result	Ref
2014	Scottish Open	David Daugaard	Raphael Beck Andreas Heinz	21–13, 21–17	Winner
2016	Dutch Open	David Daugaard	Lee Jhe-huei Lee Yang	17–21, 17–21	Runner-up
2016	Scottish Open	David Daugaard	Adam Hall Peter Mills	15–21, 21–19, 21–15	Winner

Mixed doubles

Year	Tournament	Partner	Opponent	Score	Result	Ref
2016	Dutch Open	Sara Thygesen	Søren Gravholt Maiken Fruergaard	21–18, 20–22, 21–16	Winner

  BWF Grand Prix Gold tournament

  BWF Grand Prix tournament

Men's doubles

Year	Tournament	Partner	Opponent	Score	Result
2014	Croatian International	David Daugaard	Theodor Johansen Mads Pedersen	21–8, 21–12	Winner
2014	Hellas International	David Daugaard	Frederik Colberg Mikkel Mikkelsen	0–0 retired	Winner
2014	Belgian International	David Daugaard	Jacco Arends Jelle Maas	11–10, 6–11, 8–11, 11–7, 11–9	Winner
2015	Finnish Open	David Daugaard	Andrew Ellis Peter Mills	19–21, 12–21	Runner-up
2015	Italian International	David Daugaard	Kasper Antonsen Niclas Nøhr	22–24, 14–21	Runner-up
2016	Swedish Masters	David Daugaard	Kim Astrup Anders Skaarup Rasmussen	21–19, 21–23, 21–19	Winner
2016	Finnish Open	David Daugaard	Adam Cwalina Przemysław Wacha	21–23, 21–12, 21–12	Winner
2016	Spanish International	David Daugaard	Takuro Hoki Yugo Kobayashi	10–21, 6–21	Runner-up

Mixed doubles

Year	Tournament	Partner	Opponent	Score	Result
2015	Orléans International	Lena Grebak	Chan Peng Soon Goh Liu Ying	11–21, 21–17, 21–19	Winner
2015	Irish Open	Lena Grebak	Robert Mateusiak Nadieżda Zięba	19–21, 21–18, 21–18	Winner
2016	Swedish Masters	Lena Grebak	Robert Mateusiak Nadieżda Zięba	10–21, 13–21	Runner-up
2016	Austrian Open	Lena Grebak	Matthew Nottingham Emily Westwood	21–17, 21–17	Winner
2016	Orléans International	Lena Grebak	Robin Tabeling Samantha Barning	21–14, 21–13	Winner
2016	Finnish Open	Lena Grebak	Niclas Nøhr Sara Thygesen	18–21, 23–21, 21–16	Winner
2016	Irish Open	Sara Thygesen	Robin Tabeling Cheryl Seinen	21–16, 21–16	Winner
2019	Hungarian International	Alexandra Bøje	Kim Sa-rang Kim Ha-na	12–21, 15–21	Runner-up
2019	Irish Open	Alexandra Bøje	Ronan Labar Anne Tran	21–12, 21–19	Winner
2019	Scottish Open	Alexandra Bøje	Mathias Bay-Smidt Rikke Søby Hansen	23–21, 21–16	Winner

  BWF International Challenge tournament

  BWF International Series tournament

  BWF Future Series tournament