Career
During his 16-year-long professional career, Štefulj played for several clubs in Croatia and Germany, most notably Croatia Zagreb (now Dinamo Zagreb) and Hannover 96. He retired in 2008 with NK Međimurje. Štefulj started his professional career with NK Varteks in 1992, before transferring to Croatia Zagreb in the winter break of the 1995-1996 season.
During the 1997-1998 season, he also spent a few months on loan to NK Slaven Belupo.
In 1999, he moved to German side Hannover 96, who played in the 2nd Bundesliga at the time. He established himself as a regular at the club, appearing in a total of 95 league matches over the following three seasons and helping the club gain promotion to the 1st Bundesliga in 2002.
He scored a total of 14 league goals during the three seasons. Football Club Nuremberg in February 2003.
He also helped Nuremberg return to the top flight for the 2004-2005 season.
He then returned to Hannover following the end of the 2003-2004 season, but only made 4 Bundesliga appearances for the club throughout the entire 2004-2005 Bundesliga season. In the summer of 2005, he moved to South Carolina Paderborn 07, where he only made one appearance in the 2nd Bundesliga before moving to Rot-Weiss Essen in the winter break of the 2005-2006 season and making 10 appearances for the club in the Regionalliga Nord. He also helped Essen gain promotion to the 2nd Bundesliga for the 2006-2007 season, but made no appearances in the league before leaving for NK Međimurje in January 2007.
He finished his career with Međimurje during the 2007-2008 season.
Štefulj made four international appearances for the Croatian national under-21 football team between 1993 and 1996, all in international friendlies.