The actress has set up home in New York with her husband Daniel Craig and her 6-year-old son Henry. Last year, she received official American citizenship meaning that she can now have her say in the country's elections.
She told Stylist: "I [applied for citizenship] because I thought I would go back to England for a while and lose my green card.
"I'm not going back now, but being a citizen means I can vote here, which is exciting; not just being an outsider."
The Bourne Legacy star continued: "When I come back into the country now and they stamp my passport, they say, 'Welcome home ma'am'. I think that's a lovely formality. No-one in England would ever say that."
Despite her love for her American citizenship, Weisz admitted that she does miss her friends and family in the UK.
She added: "I still have a place in London and love spending time there. I miss my friends who I grew up with, my girls. It's a different relationship."