Stefan Yanev had said Russia's actions should be labelled a "military operation", echoing the words of Vladimir Putin.
Bulgaria's defence minister has been dismissed after stating the Russian invasion of Ukraine should not be called “war”.
Stefan Yanev sparked a backlash over a post on Facebook in which he called for people "not to use lightly the term 'war'".
Instead, he suggested that it be labelled a "military operation," echoing the language of Russian President Vladimir Putin.
Yanev -- who had served as Bulgaria's caretaker prime minister last year -- had nevertheless condemned Moscow's "unacceptable aggression".
But Bulgaria's Prime Minister Kiril Petkov confirmed on Monday that Yanev had been dismissed from his post.
The decision is to be ratified later today by an extraordinary council of ministers and then by parliament on Tuesday.
"No minister in this government has the right to his own foreign policy, especially on Facebook," Petkov said in a statement.
"No minister can tell the government that his stay is a function of cabinet stability," the Prime Minister added.
"This government will not pursue stability, it will pursue the right actions and principled positions."
NGOs had been calling for Yanev's resignation for several days over his "inappropriate" behaviour, while an online petition had gathered thousands of signatures.
Petkov added it was not in Bulgaria's national interests to be "silent" on Russia's invasion of Ukraine and stated the government should "clearly express a position that condemns these policies and actions".
"When we see that one Slavic country is attacking another Slavic country in a fratricidal war, without a real reason, we must state clearly - this war must stop," Petkov told reporters on Monday.
"We, as the EU, must do everything possible to end this," he added.
In December, Yanev had been reluctant to welcome NATO troops on Bulgarian soil, arguing that "this would increase tensions in the region".
The former military general is also a close ally of Bulgarian President Rumen Radev and had previously served as deputy prime minister, before being handed the caretaker PM role last April for several months.