However, those same people also said it was unlikely the European Union would let May get the kind of Brexit deal she hopes for.
Overall, 55 percent of those surveyed thought Brexit would be good for Britain, while 19 percent thought it would be bad.
WATCH | Here's May's full speech. She reiterated commitments to a "clean Brexit" but insisted the U.K. would remain a "best friend" of the EU.
People will judge Brexit on the overall package, on whether it feels like a good deal for Britain or not.
However, as the poll noted, the numbers don't tell the full story.
Moreover, despite the support for Brexit as a whole, only 20 percent of Britons think the EU will agree to the Brexit deal she wants.