Marcus Daniell created history at Tokyo 2020, winning bronze alongside teammate Michael Venus in the men's tennis doubles. It was New Zealand's first Olympic tennis medal in 109 years. It was the second Olympic Games for Daniell. He also competed with Venus at Rio 2016, with the pair knocked out in the first round to the eventual silver medallists.

Daniell has won 5 ATP doubles titles and has been ranked as high as 34 in the world in 2018. His best showings in Grand Slam events were reaching the Australian Open doubles quarterfinals in 2018 and 2021 and the Wimbledon quarterfinals in 2019. He has played 18 Davis Cup ties from 2010-24, and won 12 doubles matches and lost six. He played three singles matches, winning two.

Daniell was a member of ATP Player Council in 2021-22 and was the ATP’s 2021 Arthur Ashe Humanitarian Award winner, following his extensive charity work. He founded High Impact Athletes in 2020, which channels charitable donations to the most effective, evidence-based charities in the world, specifically in the fields of extreme poverty, animal welfare and environmental impact. He is also a member of Giving What We Can, committing to donate a minimum of 10% of his earnings to high-impact charities for the rest of his working life.

Daniell was elected by fellow Olympic athletes to the IOC Athletes’ Commission during the 2024 Paris Olympic Games.