Oreskovich played minor hockey with the Oakville Rangers of the OMHA SCTA League, winning two provincial rep championships with the club. Following minor, Oreskovich was drafted in the 6th round by the Windsor Spitfires of the Ontario Hockey League (OHL), but he joined the Junior A ranks to maintain his eligibility for college hockey in the United States. He played the 2002–03 season with the Milton Icehawks of the Ontario Provincial Junior Hockey League (OPJHL), before joining the Green Bay Gamblers of the United States Hockey League (USHL) the following year. He recorded 37 points in 58 games and was named to the 2004 USHL All-Star Game. Following his season with the Gamblers, Oreskovich was selected in the second round, 55th overall, of the 2004 NHL Entry Draft by the Colorado Avalanche.
Recruited to play college hockey with the Notre Dame Fighting Irish of the Central Collegiate Hockey Association (CCHA), Oreskovich joined the club following his draft on a $42,000 annual scholarship. He struggled in his freshman year, recording three points in 37 games. With aspirations to turn professional sooner, he left Notre Dame nine games into his sophomore year to join the OHL, where his major junior rights had been traded on November 24, 2005, from Windsor to the Kitchener Rangers. Kitchener was Oreskovich's desired destination to play major junior, as his best friend and former minor hockey teammate Evan McGrath starred with the Rangers. In December 2005, he debuted with the Rangers, scoring goals in his first three games. He went on to record 16 points over 19 games for the remainder of the 2005–06 season.
Oreskovich attended the Avalanche's training camp for the 2006–07, where he was among the first cuts reassigned back to junior. Returning to the Rangers for a second season, he finished second in team scoring with 28 goals and 60 points in 62 games.
The following off-season, on July 7, 2007, Oreskovich was signed to a two-year, entry level contract by the Colorado Avalanche. He returned for his second Avalanche training camp for the 2007–08 season and was assigned to their American Hockey League (AHL) affiliate, the Lake Erie Monsters. Oreskovich, however, did not report to the Monsters; he was suspended by the Avalanche, before announcing his retirement from the game, citing burnout and a lost drive.
After a two-year hiatus, Oreskovich regained ambitions to play professionally and reached out to former Kitchener Rangers coach Peter DeBoer, now head coach of the NHL's Florida Panthers. He earned a try-out with the Panthers at their training camp for the 2009–10 season. He was assigned to Florida's AHL affiliate, the Rochester Americans and was signed a two-year contract with the Panthers on October 7, 2009. Within less than a month, Oreskovich was called up to the NHL and capped off his comeback by making his NHL debut with the Panthers in a 4–3 victory over the St. Louis Blues on October 31. Providing an energetic checking presence with the Panthers, he scored his first NHL goal against Jonathan Quick of the Los Angeles Kings in a 4–3 defeat on November 16. He split his professional rookie season between the Panthers and Americans, scoring six points over 50 games in the NHL and 15 points over 34 games in the AHL.
During the 2010 NHL Entry Draft on June 25, 2010, Oreskovich was traded to the Vancouver Canucks along with defenceman Keith Ballard in exchange for Michael Grabner, Steve Bernier, and Vancouver's first round pick, the 25th overall selection, used to select Quinton Howden. Following the pre-season, the Canucks assigned Oreskovich to their AHL affiliate the Manitoba Moose. Shortly after returning from a shoulder injury that sidelined him for 15 games, he was recalled by the Canucks on February 10, 2011. After making his Canucks debut two nights later in a 4–2 win against the Calgary Flames, he spent the remainder of the regular season being assigned back-and-forth from the Canucks and Moose. Receiving five call-ups until the end of the campaign, he totalled three assists over 16 NHL games and 12 points (4 goals and 8 assists) over 40 AHL games. Oreskovich remained with the Canucks for the entire 2011 playoffs, dressing for 19 games (not recording any points) as the Canucks lost in the Stanley Cup Finals to the Boston Bruins.
During the off-season, Oreskovich became a restricted free agent on July 1, 2011. Without arbitration rights (due to his lack of experience in the league), negotiations with Vancouver continued through the summer; media speculated Oreskovich was demanding either a one-way or a multi-year deal. As training camp neared, Oreskovich agreed on a one-year, two-way contract worth $605,000 in the NHL and $105,000 in the minors. Regarding initial Oreskovich's contract holdout, Canucks assistant general manager Laurence Gilman commented, "Victor made great strides last year, but he's still a developing player." During the off-season, the Canucks chose not to re-sign bottom-six forwards Raffi Torres and Tanner Glass, seemingly increasing Oreskovich's chances to remain with the team. However, prior to the start of the season, he was waived by Vancouver after the team picked up fourth-line winger Dale Weise from the New York Rangers. After clearing waivers, he was assigned to the Canucks' new AHL affiliate, the Chicago Wolves on October 5, 2011. Returning to the AHL, he suffered a concussion that sidelined him for several games. Following his recovery, he was called up to the Canucks on December 5, 2011, to replace injured winger Chris Higgins. He appeared in one game during the call-up before being sent back down.
Oreskovich is of Croatian descent. He attended high school at Notre Dame Catholic School in Welland, Ontario, as well as at Iroquois Ridge High School in Oakville, Ontario. While playing college hockey with the Notre Dame Fighting Irish, he studied finance before dropping out to join the major junior ranks. He later re-enrolled at University of Notre Dame during his two-year hiatus from his hockey career, to complete his finance degree. In 2015, Oreskovich enrolled at the Richard Ivey School of Business to complete his master's degree in Business Administration.