Steve Staios was selected by the St. Louis Blues in the second round of the 1991 NHL Entry Draft, but he never played a game for the team. A graduate of the OHL's Niagara Falls Thunder and Sudbury Wolves, Staios played three seasons in the OHL before making his professional debut in 1993-94.
After four seasons in the AHL with the Peoria Rivermen, Staios was traded to the Boston Bruins during the 1995-96 season. Upon his arrival with Boston, Staios went on to make his NHL debut with the club, while seeing limited action with the club's AHL affiliate in Providence. In the latter stages of the 1996-97 season, the Vancouver Canucks claimed Staios off waivers. The mobile defenseman went on to play the next two seasons in Vancouver before being selected by the Atlanta Thrashers in the 1999 Expansion Draft. Staios went on to play two seasons in Atlanta, establishing a career high in points with 22 (9-13-22) during the 2001-02 season before being traded to the New Jersey Devils later that summer. He was traded back to the Thrashers a month later when he took on the captaincy of the young team. Staios then signed as a free agent with the Edmonton Oilers in 2001 has been one of the team's more reliable players, bettering his offensive output of the 2001-02 season, with 28 points (6-22-28) during the 2003-04 season.
In the 2005-06 playoffs Staios and the Edmonton Oilers made a surprise run to the Stanley Cup Finals. Appearing in each of the Oilers playoff games, the defenceman and his club would finish just one win shy of winning the Stanley Cup in 2006.
On the international stage Staios helped Canada capture a gold medal at the 2003 and 2004 World Championships, and silver at the 2008 tournament.
On March 3, 2010, the NHL trade deadline, Staios was traded to the provincial rival Calgary Flames in exchange for defenseman Aaron Johnson and a conditional draft pick.