Born in Landstuhl, Keßler was raised in nearby Weselberg, where she attended kindergarten and primary school.

[7] She helped the team finish the regular season at the top of the league table with a 19–1–2 record scoring 11 goals.

[8] The team clinched the 2009–10 UEFA Women's Champions League after defeating Olympique Lyonnais in penalty kicks.

[12] She captained the team to win the 2012–13 UEFA Champions League after defeating Olympique Lyonnais 1-0 in the final.

[13] In 2014, Keßler led Wolfsburg to championships in the Frauen Bundesliga and UEFA Women's Champions League.

[14] Wolfsburg became the first German team in the history to win the treble of Frauen-Bundesliga, DFB-Pokal Frauen and the renamed UEFA Women's Champions League.

She made her debut for the senior national team at the 2010 Algarve Cup on 26 February 2010 in a match against Finland after coming on as a 46th-minute substitute for Lena Goeßling and scoring her first international goal in the 77th minute.