Kiplagat studied at the Sirgoech Secondary School in Iten and she hoped to get a scholarship in the United States. She failed to get a scholarship, but had a successful start for her running career. She won the silver medal in 5000 m at the 2006 World Junior Championships. At the 2007 World Cross Country Championships she finished fifth in the senior race, while the Kenyan team of which she was a part won the silver medal in the team competition. She was out of activity in 2008 after becoming a mother. After the motherhood, she started the collaboration with the Italian Coach Renato Canova, which produced great results, continuing today. She made comeback in early 2009 by winning the Elgoibar Cross Country and Cross Internacional de Itálica meetings in Spain. She won the women race at the 2009 IAAF World Cross Country Championships ahead of compatriot Linet Masai. She became the second Kenyan to win the long race at the World Cross Country Championships, the first one was Hellen Chepngeno, who won in 1994. On 14 June 2009 she finished 2nd in the 10,000 m race in Utrecht. Kiplagat's time, 30:11.53 was a Kenyan record. The previous national record, was set by Linet Masai at the 2008 Olympics. Florence Kiplagat did not defend her world cross-country title in 2010, as she was recovering from an injury. She made her debut over the half marathon distance in September 2010 and managed to win first time, beating Peninah Arusei to the Lille Half Marathon title with a time of 1:07:40. This was enough to gain selection for the 2010 IAAF World Half Marathon Championships and she defeated Dire Tune in the final stages of the race to take the women's world title in only her second outing over the distance. She also led Kenya to another world team title alongside Arusei, her Lille rival. Having taken global titles in cross country and road running, she stated her intention to focus on reaching the podium on the track at the 2011 World Championships in Athletics and the 2012 London Olympics. She ran in the 15K race at the Zevenheuvelenloop and was runner-up to Genet Getaneh, but at the Sapporo Half Marathon she continued her undefeated streak over that distance. Kiplagat's marathon debut came at the 2011 Berlin Marathon and she started quickly, outpacing both Paula Radcliffe and Irina Mikitenko to claim her first victory in 2:19:44 hours – the third fastest run by a woman that year. She was the favourite for the 2012 Egmond Half Marathon, but finished as runner-up behind Meseret Hailu. She moved up to third on the all-time lists with a winning run of 1:06:38 hours at the Roma-Ostia Half Marathon. She turned to the 10,000 m at the Prefontaine Classic and claimed the runner-up spot behind Tirunesh Dibaba. She failed to make the Olympic team in the event, however, narrowly finishing fourth at the Kenyan trial race. She missed the rest of 2012, but returned at the RAK Half Marathon in February the next year and had her second fastest ever result, although the depth of the race left her in fifth. She was one of the favourites entering the 2013 London Marathon but she underperformed, coming sixth in a time of 2:27:05 hours. In August she won the half marathon of Klagenfurt in 70:06 minutes. The 2013 Berlin Marathon saw her top the field with her winning time of 2:21:13 hours, beating Sharon Cherop by over a minute. The following month she won the Great South Run with a time of 53:53 minutes – two minutes clear of the rest of the competition. A win at the Delhi Half Marathon closed a successful year. Kiplagat broke the half marathon world record by a significant margin at the Barcelona Half Marathon in February 2014, running 1:05:12 hours to beat Mary Keitany's old mark by 38 seconds. She also took the world record for the 20 km distance as well with a time of 1:01:56 hours. Kiplagat finished in second place at the 2014 London Marathon in a time of 2:20:24, being narrowly defeated by her compatriot Edna Kiplagat. In 2015, Kiplagat set the Half Marathon World Record with a time of 1:05:09 on 15 February in Barcelona, Spain. She continued her 2015 season success with a victory at the 2015 Chicago Marathon with a time of 2:23:33 after pulling away from the competition in the 25th mile of the race.
