Kramer, who officially takes over on Tuesday, signed a deal until June 2015.
"Although the weekend defeat makes things very difficult for us we need to look forward," Fuerth president Helmut Hack said in a statement on Monday.
Fuerth lost 3-0 at home to relegation rivals Hoffenheim on Saturday to stay in last place on 14 points with their opponents on 19. Augsburg are a further two points ahead in the relegation playoff spot with nine games left in the season.
"Frank will push our fresh start forward so that we can look forward with a sense of confidence," Hack added.
Kramer will be assisted by Ludwig Preis, who briefly took over as interim coach after the sacking of Mike Bueskens in February.