Mr Buttigieg in April last year flew with his husband Chatsen from Maryland’s Joint Base Andrews to Rotterdam in a government plane, according to a calendar obtained by non-profit Americans for Public Trust.
On Thursday, Fox News anchor Bret Baier pulled up Mr Buttigieg’s travels when the secretary pointed to previous instances where US officials brought their spouses.
They were, however, not subjected to criticism, he added.
“Was that reimbursed?” Baier asked, adding that it was “one of the controversies”.
"Of course not,” the transportation secretary replied.
“I led a presidential delegation to support American wounded warriors and injured service members – the Invictus Games as has been tradition for many years. “
The Games were founded by Prince Harry in 2014 to honour military veterans and wounded soldiers.
“I led the American delegation as one of the great honours of my time in this job. And the diplomatic protocol on a presidential delegation is that the principal is often accompanied by their spouse. It was a great trip. Incredible,” he continued.
Mr Buttigieg said that, prior to his trip, several American officials have had their partners accompanying them to the Games.
“Before me, it was the secretary of the army under president Trump who took that trip with his wife. Before that, it was Mrs Trump as first lady who went. Before that, Mrs Obama did the same thing.
“And I guess the question on my mind is, if no one’s raising questions about why secretary [Mark] Esper and his wife led that delegation, as well they should have, then why is it any different when it’s me and my husband?”
“Understood,” replied Baier.
Mr Buttigieg had to jump to his husband’s defence earlier as well. The secretary’s husband had tweeted that supreme court justice Brett Kavanaugh wanted “some privacy to make his own dining decisions” when a group of protesters interrupted his dinner.
“Look, when public officials go into public life, we should expect two things — one, you should always be free from violence, harassment and intimidation.
“And two, you’re never going to be free from criticism or peaceful protests with people exercising their First Amendment rights,” Mr Buttigieg said.