Pinsent was born in Dorset, England, and began rowing at school. After rowing at the World Junior Championships in 1987, he was selected in 1990 to row with Steve Redgrave in the coxless pair. This involved taking a year out of his undergraduate studies at the University of Oxford. It was the beginning of a long partnership, and the pair won the World Championships in 1991, and at the Olympic Games in 1992, 1996 and 2000.