[2] He won the 200 m freestyle long course at the 2008 European Aquatics Championships final, finishing in a time of 1:46.59.

On 26 July 2009, Biedermann won the 400 m freestyle final at the 2009 World Aquatics Championships.

He passed 1500 m Olympic champion Oussama Mellouli in the final 50 metres and finished with a time of 3:40.07, shaving nearly three seconds off his own personal best and bettering Ian Thorpe's 2002 world record by one-hundredth of a second.

[citation needed] In the 2010 Short Course Worlds, Biedermann won gold in the 400 m freestyle, beating Oussama Mellouli again in a race that unfolded almost identically to their race in Rome the previous year.

However, Biedermann got the better of Phelps in the relay lead-off leg by beating him by 0.33 seconds.