Tarrant won a gold medal in the eight at the 2014 World Championships in Bosbaan, Amsterdam.

[1] He was part of the British team that topped the medal table at the 2015 World Rowing Championships at Lac d'Aiguebelette in France, where he won a gold medal as part of the coxed pair with Nathaniel Reilly-O'Donnell and Henry Fieldman.

[2] He won a bronze medal at the 2017 World Rowing Championships in Sarasota, Florida, as part of the coxless four.

[3] He then won a bronze medal at the 2018 World Rowing Championships in Plovdiv, Bulgaria, as part of the eight with James Rudkin, Alan Sinclair, Tom Ransley, Thomas George, Moe Sbihi, Oliver Wynne-Griffith, Will Satch and Fieldman.

[4] He won another bronze medal the following year at the 2019 World Rowing Championships in Ottensheim, Austria as part of the eight with George, Rudkin, Josh Bugajski, Sbihi, Jacob Dawson, Wynne-Griffith, Thomas Ford and Fieldman.