The Grey's Anatomy star relocated to California with his partner Jane and their two children after landing a leading role in TV series Journeyman in 2007. It was cancelled after one season, but the following year (08) he began playing Dr. Owen Hunt in the medical drama.

MCKidd and his wife attended an oath ceremony at the U.S. Court House in Los Angeles this week (beg17Aug15) and the actor later shared a picture on showing the couple holding their certificates while standing with their kids.

He added a caption thanking bosses at the U.S. Citizenship and Immigration Services (USCIS) for their help, writing, "New U.S. citizen thank you all at @USCIS - a wonderful ceremony - proud and emotional."

MCKidd is latest celebrity to become a U.S. citizen this month (Aug15) following British actress Emily Blunt and Matthew MCConaughey's Brazilian wife Camila Alves.