Graduated from South High School in Minneapolis, Minnesota in June of 1996, then attended SUNY in Purchase, New York. By April of 1997, he was offered the role of Michael Fitzgerald in the short-lived American television series Cracker: Mind Over Murder. Josh started off doing small plays and national commercials, but is beginning to break into the big-screen movie business with his starring role in Halloween H20: 20 Years Later.


Chosen as one of Teen People Magazine's "21 Hottest Stars Under 21." [1999] Auditioned for Remember the Titans (2000). Has three younger siblings: Jessica, Jake, and Joe. He went to high school with actress Rachael Leigh Cook. Josh also attended Cretin-Derham Hall in St. Paul Minnesota before attending South High School. Recently moved back to Minnesota (March 2002). One of Teen People's 25 Hottest Stars under 25 (2002) Was scheduled to speak at a political rally in support of Senator Paul Wellstone the weekend the Senator was killed along with 7 others in a plane crash. On October 26th 2002 (the day after the Senator's death), Hartnett appeared at a peace rally in St. Paul, Minnesota and spoke a few words in rememberance. Is a vegetarian. Was voted Bliss magazines 3rd sexiest male. Was set to play the role of Tino in Deuces Wild (2002) but dropped out when he won the role of Danny Walker in Pearl Harbor (2001). The Tino role eventually went to James Franco. Director Sofia Coppola directed both Josh and his girlfriend Scarlett Johansson, but not in the same movie. Scarlett was in Coppola's Lost in Translation (2003) and Josh starred in The Virgin Suicides (1999). The film Hero Wanted (2008) was originally conceived as a starring vehicle for him although the script at the time was very different. Friends with Ben Affleck and Jason Isaacs. From 2004 to late 2006 was the boyfriend of Scarlett Johansson.