Lutui was born in the South Pacific nation of Tonga, but grew up in the Phoenix suburb of Mesa.
The new citizens took the Oath of Allegiance on Friday at the South Mountain Community College gymnasium.
Lutui, a second-round draft pick out of Southern California in 2006, started the citizenship-application process in 2001 but the Sept. 11 attacks caused delays. Some of the final requirements were met last fall.
Now that he's officially an American citizen, Lutui says one of the first things he'll do is throw away his green card.