Haggett was born in Dulwich, London, England and was a member of the Croydon HarriersAthletics Club. In 1986, she cleared 1.81 metres as a 14-year-old. In 1990, still only eighteen, Haggett was the UK's number one female high jumper, winning the AAA Championships with a personalbest of 1.88 m, defeating Olympic finalist Janet Boyle. A week later at the World Junior Championships in Plovdiv, Bulgaria, she again cleared 1.88 m to win the bronze medal. She would remain the only British woman to win a medal at the World Junior Championships in the high jump until Morgan Lake won gold in 2014. She ended the season by competing at the European Championships in Split. As the only British entrant, she managed 1.80 m and was eliminated in the qualifying round. Haggett began the 1991 season by improving her personal best to 1.91 m at a meeting in Chania, Greece on 2 June. Although she would not improve on this for the rest of the year, she had another consistent season. Also in June, she won the UK Championships title with 1.85 m. In July, she cleared 1.88 m to finish second at the AAAs Championships behind Debbie Marti. In August, she cleared 1.89 m for fourth at the European Junior Championships in Thessalonika. In 1992, at the AAAs Championships, incorporating the Olympic trials, Haggett won her second AAAs title with 1.89 m but failed to earn Olympic selection. Her 1.91 m best from the previous year was one centimetre short of the qualifying standard. After a year out with an injury, Haggett returned in 1994 and earned selection for both the European Championships in Helsinki and the Commonwealth Games in Victoria. At the Europeans, she managed only 1.75 m in qualification. She fared better at the Commonwealth Games, clearing 1.88 m to finish fifth in the final. In 1995, Haggett was the UK number one for the second time, with a season's best of 1.90 m. At the AAAs Championships, she won on countback ahead of Diana Davies and Debbie Marti, to earn World Championships selection. All three cleared 1.85 m. At the World Championships in Gothenburg, she cleared 1.75 m and was eliminated in qualification. Haggett earned Olympic selection in 1996 by achieving her lifetime best of 1.92 m at the AAAs Championships in Birmingham. She finished second to Debbie Marti who cleared 1.94. At the Atlanta Olympics, although failing to reach the final, she produced her best jump in a major championships with 1.90 m, defeating Marti, who cleared 1.85 m. Haggett and Marti were the last British women to compete in an Olympic high jump competition until Morgan Lake competed in 2016. Atlanta would prove to be Haggett's final major championships. As of 2015, Haggett's best jump of 1.92 m from 1996 ranks her 11th on the UK all-time list. Her 1.91 m from 1991, when she was 19, stood as the UK junior record for 23 years. Susan Jones equalled the record in 1997 before Morgan Lake broke it in 2014 by clearing 1.93 m.
