The senior MP said Labour would “work around” the controversial US leader as they do not “agree” with him.
Her comments on ITV come weeks before President Trump will visit the UK on a state visit, which will take place from 3-5 June.
Speaking on Good Morning Britain (GMB), Ms Thornberry said: “What you do is you work with other people in the administration.
“I have been working with people in the Senate and in Congress.
“There are lots of allies there, there are lots of people who share our values.
“That is how you do it.”
Ms Thornberry said she would have interaction with Mr Trump as Foreign Secretary but she would be “quite clear” with him about what she disagrees with.
She also said in the interview it is about time Britain “stands up of what it believes for as a country and holding our heads a bit higher”.
Ms Thornberry said Trump has appointed ‘two extremists’ to Supreme Court and she does not want to work with him.
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She said last month that the US president is a “threat to our world order” and does not deserve a state visit.
Theresa May has said President Trump’s visit is a chance for the UK and the US to strengthen their “already close relationship”.
Foreign secretary Jeremy Hunt said the country should offer "the best possible welcome" to Trump.