Starting 2000, Radcliffe won the Stormont Cross Country race for a third time. Radcliffe then finished fourth in Durham. Radcliffe then sustained a knee injury. For the European Cup, Radcliffe joined a host of other British athletes by pulled out injured. However, Radcliffe soon returned to the track for the first time since March after a virus, a knee operation and a calf muscle tear had kept her out; to race over 1,500 metres in Barcelona. In her first race since the World Cross Country, Radcliffe finished 11th. At the London Grand Prix, Radcliffe finished second, one second outside of her British record, in only her second track race of the season. At the Weltklasse Zürich IAAF Golden League meeting Radcliffe competed in the 3,000 metres and finished in fourth place. At the UK trials won the 5,000 metres title. The British Grand Prix saw Radcliffe race over 3000 metres, where once again she finished third. At the 2000 Olympic Games in Sydney, Radcliffe finished sixth in her 10,000 metres heat to qualify for the final. In the final Radcliffe set a new British record, but crossed the line in fourth and was highly disappointed to miss out on a medal. Radcliffe returned to action by winning the BUPA Ireland five-mile race. At the Great North Run, Radcliffe ran a new European record for the half marathon, as she won the race in a time of 67 minutes and 7 seconds. Radcliffe was then selected for the 2000 IAAF World Half Marathon Championships in Mexico. Radcliffe won her first World title, despite suffering a panic attack when her nose tape, designed to help her breathe, fell off halfway round. The good run of form came to an end, when she turned her attention to the Cross Country events and finished third in Brussels. Radcliffe confirmed that her last race of the year would be the Great North Cross Country. There Radcliffe defeated Tulu by seventy-five seconds, in eight inches of snow.
She won back-to-back titles in the 2000 and 2001 IAAF World Half Marathon Championships, winning a third title in 2003.