The 29-year-old striker has been under contract with Borussia Dortmund since July 2022. He previously played for Ajax. As of June 2023 (reference date for all stats), he has made 22 appearances for BVB across all competitions (nine goals / five assists).

His story moved the entirety of German football. His determined battle against Cancer impressed everyone. In January 2023, after an enforced six months of absence, with two operations and four chemotherapies, Haller ceased being a patient and returned to being a professional footballer. “His personal story is the fairytale of last season, perhaps the biggest fairytale in all of European club football,’’ said Hans-Joachim Watzke in an interview with member’s magazine Borussia (June 2023 edition). “I still have clear memories of when he told us he’d been diagnosed with cancer at our summer training camp in Bad Ragaz. He underwent two operations, had to go through four stages of chemotherapy. During this whole time he showed such incredible strength, which even helped to lift other people around him up. After just six months he was back out on the pitch giving it his all. What incredible strength the guy has! It’s truly impressive.”

The striker played in all 19 league games after the winter break (15 times as a starter). With him in the side, the Black & Yellows picked up an average of 2.4 points per game, whereas before his return they were averaging just 1.7. “At the time he made his comeback, we weren’t even in the Champions League places. If I remember correctly, our attacking wide players didn’t score a single goal between them in the 15 matchdays. With Sébastien in the line-up, the group developed into the league’s most potent offensive unit,’’ recalls Watzke. Haller himself netted nine goals, tying him level with Julian Brandt and Donyell Malen as BVB’s top scorer for the whole season, and putting him well out on front of the chart for the second round of fixtures. During his time at Eintracht Frankfurt, the Frenchman made a name for himself as a towering and imposing centre-forward who relishes the physical side of the game. He has proved as much during his time at BVB. He won an impressive 53% of his challenges in his debut season in Black & Yellow and has become the side’s go-to target man for long balls.

"You can get cancer, but you can also beat it. That's what I've learned in the past six months," explained Sébastian Haller in an interview with the members' magazine Borussia (March 2023 issue), stressing that he "never doubted that I would return to the pitch. I remember very well the meeting with our doctor, when he told me: Okay, Sébastien, you can get back to training. That was around 20 December. I knew then that the tumour was out and there was nothing left of the disease in my body."

Haller was signed ahead of the 2022/23 season as the successor to striker Erling Haaland, who moved to Manchester City. The previous season, Haller shone for Ajax in the Dutch Eredivisie, finishing the campaign as the top scorer domestically (21 goals), while also impressing in the UEFA Champions League. His total of 11 goals in the competition placed him third in the scoring charts. Haller scored in every game in the group stage - something only ever achieved prior by Cristiano Ronaldo. Haller had also proven himself to be a reliable goalscorer in the Bundesliga. Between 2017 and 2019, he scored 24 goals in 60 games in the Eintracht Frankfurt jersey.

Sébastien Haller was born on 22 June 1994 in Ris-Orangis, just outside of Paris, to a French father and an Ivorian mother. He therefore has citizenship of both countries. Internationally, he plays for his mother's homeland and has made 15 senior international appearances to date. He scored on his debut on 12 November 2020 in a 2-1 win over Madagascar. He represented France as a youth player, scoring 25 goals in 51 youth internationals from U16 to U21. Haller did judo as a child, which perhaps explains his incredible flexibility.

In June 2011, Haller signed his first professional contract as a 17-year-old with AJ Auxerre and made his first appearance in France's second tier in July 2012. In January 2015, he moved to FC Utrecht. He described his two-and-a-half-year stint in the Eredivisie, where he scored 51 goals in 98 games, as a turning point in his career. Haller then moved to Eintracht Frankfurt for the 2017/18 season, where he helped the Hessians lift the DFB-Pokal trophy in May 2018 (beating Bayern Munich 3-1 in the final).. In 2018/19, the 1.90-metre-tall striker was directly involved in 24 of Frankfurt's 60 Bundesliga goals, netting 15 times and providing nine assists to teammates. And it could have been even more if he hadn't suffered an injury on Matchday 27 (abdominal muscle strain).

The Cote d’Ivoire international then moved to the Premier League to join West Ham United ahead of the 2019/20 season. He scored three goals in his first three league games; after a year-and-a-half in England he'd netted 14 in 54 appearances. Haller moved back to the Netherlands to join Ajax in January 2021, linking up with former coach Erik ten Hag, who helped develop him into a top striker at Utrecht. During his time in Amsterdam, he won the league title in 2021 and 2022 (as top scorer), not to mention the cup in 2021.

Haller is married and has two children (daughter Chiara and son Eden). He is a humble and down-to-earth person.