"There were many reasons to release Matthaus, not only the poor results in the last matches. Pressure and negativity had also piled up in the squad, so the change was necessary," Bulgarian Football Union president Borislav Mihaylov said.
The legendary German midfielder, 50, was the first foreigner to take over as coach of Bulgaria when he was appointed in September last year with a remit to qualify for EURO 2012.
However, Matthaus leaves with Bulgaria out of the running for a place in next year's finals in Ukraine and Poland, having managed just one win and five points from seven games in qualifying Group G.
Matthaus had previously blamed poor discipline and lack of will to win among the players as the reasons for his team's poor performances.
He had, however, hoped to renew his contract, which was due to expire in November, to lead Bulgaria in the 2014 FIFA World Cup™ qualifiers.