The Morning Joe co-anchor said during Friday's broadcast she wanted to address the "terrible choice of words" of Wednesday's show, which saw her referring to the Secretary of State as "a wannabe dictator's butt boy".
"Butt boy" is a homophobic slur. Brzezinski used it during a discussion of Pompeo's insistence that there is "no direct evidence" linking Saudi crown prince Mohammed bin Salman to the killing of journalist Jamal Khashoggi, despite intelligence reports to the contrary.
"I wanted to address a term that I used on this show on Wednesday that was vulgar," Brzezinski said on Friday's show.
"I knew it right away and I tweeted that it was a terrible choice of words and that I was sorry, but please allow me to say this face-to-face. The term is crass and offensive and I apologise to everyone, especially the LGBTQ community and to my colleagues for using it."
She added: "It was a mistake. My father would have found it so unbecoming and disrespectful and he would have told me.
"I will work hard to be better. But I just wanted to say on camera, looking the viewers straight in the eye, I am really, really sorry."
Donald Trump had previously claimed on Twitter that if a Conservative had used the slur, they would have been "banned permanently from television", while Brzezinski would "probably be given a pass".
Brzezinski, who was off on Thursday due to a family matter, apologised on the platform earlier this week, saying she had committed a "super bad choice of words".
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