He signed for Vålerenga on 9 February 2007, after a rather turbulent stay in FK Austria Wien. He was contemplating an offer to move to the Chicago Fire of Major League Soccer in July 2006. Groclin complained to FIFA, because they felt that Austria Vienna did not have the right to sell Mila. At that time he was only on loan from the Polish club.
Sebastian Mila joined Polish First Division side ŁKS Łódź on loan in the Polish transfer window 2008.
In July 2008, he signed a four-year contract with Polish club Śląsk Wrocław. In the spring of 2009, in his first year with the club, he led the team to the Polish Cup trophy. As a captain in 2011 he led the team to a 2nd place finish, a year later he led Śląsk to its first championship in 35 years.