Chirag Sen started playing badminton at a young age under the guidance of his father, DK Sen, who won several medals competing in All India Civil services tournaments. He, in fact, played a crucial role in the setting up of the SAI centre in Almora, which has produced some quality players like 2023 national champion Anupama Upadhyaya.

Sen honed his skills at the Prakash Padukone Badminton Academy in Bangalore. In 2014, he won the silver medal in the boys' singles event at the Youth Olympic Games held in Nanjing, China.

Sen clinched the men's singles title at the Bulgarian International Championships in 2017. The same year, he won the India International Challenge and reached the semifinals of the Vietnam Open Grand Prix.

In 2018, Sen secured the gold medal in the men's singles event at the Asian Junior Championships in Jakarta, Indonesia. He became the third Indian male player to win the prestigious title after Gautam Thakkar and Sameer Verma.

Sen won the Belgian International title in 2019 and reached the finals of the Polish Open and the China Masters. His performances helped him break into the top 100 of the Badminton World Federation (BWF) rankings.

Chirag has been a regular on the domestic circuit in recent years. He won the 2020 Kenya International challenge but had not yet achieved a major breakthrough on the senior international circuit.

In the same year, Chirag Sen clinched a bronze medal at the 29th FAJR Badminton International Challenge held in Shiraz, Iran from February 4 to 8. In the men's singles semi-final, Sen lost to Belgium's Maxime Moreels by 21-16, 18-21, and 21-23 after putting up a strong fight. The gold medal went to China's Xiaodong Sheng, who defeated Moreels in the final by 21-17 and 21-12. Sen defeated Iceland's Kari Gunnarsson 21-14, 21-8 in the quarter-finals and Iran's Amir Jabbari 21-11, 21-17 in the pre-quarterfinals.

The year 2021 proved successful for Sen. He began by winning the Uganda International Series, followed by his maiden BWF World Tour title at the Dutch Open. Sen's biggest achievement came at the BWF World Championships in Huelva, Spain, where he clinched the bronze medal in the men's singles event. He became the third Indian male shuttler to win a medal at the World Championships after Prakash Padukone and B. Sai Praneeth.

In 2023, Chirag Sen claimed the men's singles title at the Senior National Badminton Championship. In the final in Guwahati, Chirag defeated fourth seed M. Tharun 21-14, 13-21, 21-9 to win his first national crown. This is a title that has eluded his younger brother Lakshya, who finished as runner-up in 2017 and 2019.

Chirag, is currently ranked world no. 97. Looking ahead, Chirag will have his brother Lakshya as a  partner as he gears up for upcoming events like the Malaysia Open, India Open and Indonesia Masters on the BWF tour.