Henderson began sailing aged 13. After spending a short period of time with the Sea Cadets, she decided to pursue a career in sailing. Following a season working with "Girls for Sail" (the UK's only all-female sailing school), Henderson skippered three ARC Trans Atlantic races, twice as youngest skipper in the race. She has raced three Caribbean seasons, skippered the RORC Caribbean 600, competed in two editions of the Fastnet Race, and gained further experience teaching and offshore racing in Europe. She was selected as skipper of Visit Seattle in the 2017/2018 Clipper Round the World Yacht Race.
Two days after her 25th birthday, Henderson skippered Visit Seattle to second place in the 2017/2018 Clipper Round the World Yacht Race. She was the youngest skipper in the Clipper Round the World Yacht Race history. The same race saw Wendy Tuck become the first woman to win a round the world race.
- "British female set to become youngest skipper in Clipper Race history — Practical Boat Owner". Practical Boat Owner. 16 March 2017. Retrieved 29 July 2018.
- "Nikki Henderson". Clipper Round the World. Retrieved 29 July 2018.
- Leona O'Neill (10 July 2018). "Clipper Round the World Yacht Race: 'Girl power' as skipper Nikki's yacht is first across the line in Londonderry". Belfast Telegraph. Retrieved 28 August 2018.
- Adams, Joel (28 July 2018). "Female skipper sails into history as youngest to finish world race". The Daily Telegraph. ISSN 0307-1235. Retrieved 29 July 2018.
- "The Maiden Factor: Maiden crew". Retrieved 28 November 2018.
- Zhou, Naaman (13 November 2019). "Greta Thunberg to hitch a ride to Europe with Australian YouTube influencers". The Guardian. Retrieved 13 November 2019.