[14] In his junior year, Rosen won the 2011 U.S. K-12 Championship with a perfect 7-0 score, beating then-IM Marc Arnold in the final round.

[15] US Chess called his clean sweep "one of the outstanding individual achievements in this tournament's history",[15] and the Skokie Village Board named May 16, 2011, Eric Rosen Day.

[10][17] He had been offered a full ride chess scholarship by the University of Texas at Dallas, but Rosen turned it down as it would have seen him playing for the B-Team.

[18] Instead, Michael Auger, the Illini Chess Club President and Rosen's future roommate, convinced him to study at Illinois.

[10] Rosen placed 9th in the 2011 World U-18 Championship in Caldas Novas, Brazil, with 6 out of 9 points, in doing so earning his first International Master norm.

[22][16] However, in June 2013, Rosen achieved his second IM norm, with a tied first place finish at the 29th North American Masters in his hometown of Skokie, Illinois.

[16] With his final IM norm won, and a rating over 2400, Rosen was awarded the title of International Master in September 2015 at the 86th FIDE Conference in Abu Dhabi, UAE.