De Witte (right) with her sister Lisanne at the 2016 Summer Olympics
In June 2016, De Witte won the silver medal in the 400 m at the Dutch Championships. Her time of 53.47 seconds ranked second behind only her sister Lisanne.
De Witte competed at the European Championships in July 2016.[3] In the 200 metres, she finished 16th in the semifinals and did not advance to the final. She ran in the heats and the final of the women's 4 × 400 metres relay, and the Dutch team finished seventh.
In July 2017, De Witte competed in the 400 m at the European U23 Championships. She ran her personal best time of 52.15 s in the heats to qualify for the final. In the final, she ran 52.51 s to win the bronze medal.
In August 2018, De Witte competed at the European Championships. She ran in the heats of the 400 m. She had a time of 52.57 s and did not advance to the semifinals.
In July 2019, De Witte competed in the 400 m at the Summer Universiade. She finished 16th in the semifinals at 54.45 s and did not advance to the final.
In June 2021, De Witte won the silver medal in the 400 m at the Dutch Championships with a time of 53.38 s, finishing behind her sister Lisanne. Laura was then named to the Olympic team.
