"We need to go down this path if we are to exhaust all chances of staying up," club chief Stefan Kuntz said.
"After the 4-1 defeat by Schalke 04 (on Sunday) and after many intensive discussions we were convinced we had to take this step.
"We took many measures in the past weeks and months to get the team back to success. Unfortunately they did not work."
Assistant coach Oliver Schaefer and goalkeeping coach Gerry Ehrmann will take over on an interim basis with Kurz's successor to be announced shortly, Kuntz said.
Kaiserslautern are five points off the relegation play-off spot.
Kurz, whose assistant Guenther Gorenzel was also sacked, took over in 2009 and led the Red Devils back to the Bundesliga with the club finishing seventh in their first season back in top flight last year.