Sen was born in Almora, Uttarakhand. His father, D. K. Sen, is a coach in India. Lakshya trained at the Prakash Padukone Badminton Academy and showed his talent early on. In 2016, he had a successful year in the junior circuit, winning a bronze medal at the Junior Asian Championship.

In February 2017, Sen became the number one junior singles player in BWF World Junior rankings. He won the men's singles title at the 2016 India International Series tournament. At the 2018 Asian Junior Championships, he defeated top-seeded Kunlavut Vitidsarn to win gold.
Sen's transition to senior-level badminton was marked by several victories. He won the Belgian International tournament and clinched his first BWF Tour title by winning the Dutch Open men's singles title. In November 2019, he won the SaarLorLux Open and the Scottish Open.
In December 2021, Sen reached the World Championships semifinals, securing a bronze medal. In January 2022, he won his first Super 500 title at the India Open by defeating Loh Kean Yew. He reached the finals of the All England Open but lost to Viktor Axelsen.
Sen was part of the Indian team that won the Thomas Cup in 2022 by defeating Indonesia. He also became Commonwealth champion at the 2022 Commonwealth Games and helped India win silver in the mixed team event.
In February 2023, Sen was part of the Indian team that clinched bronze at the Badminton Asia Mixed Team Championships. On July 9, he defeated China's Li Shifeng to win the Canada Open.
Lakshya Sen received the Arjuna Award in 2022 for his contributions to badminton in India. His record against top players remains impressive as of April 2024.
Lakshya Sen continues to be a prominent figure in Indian badminton with his consistent performances and dedication to the sport.Sen was born in Almora, Uttarakhand. His father, D. K. Sen, is a coach in India. Lakshya trained at the Prakash Padukone Badminton Academy and showed his talent early on. In 2016, he had a successful year in the junior circuit, winning a bronze medal at the Junior Asian Championship.