Rouble was elected as MLA for the newly created riding of Southern Lakes on November 4, 2002. He joined a majority government under leader Dennis Fentie, whose Yukon Party had just defeated the Liberals. Rouble served as a backbench MLA in his first term and Deputy Speaker of the Legislative Assembly, as well as Yukon Party Caucus Chair. He was re-elected in the 2006 Yukon election and this time elevated to Cabinet as Minister of Education. He was sworn in on October 28, 2006. He remained Minister of Education throughout his second term, serving both Premier Fentie and his successor, Darrell Pasloski. Rouble's mandate as Education minister was criticized by the media, with the Yukon News commenting that Rouble "made a fetish of hiring consultants to produce reports long on abstract gobbledegook and short on concrete goals." Rouble - and his department - was also criticized for his department's inability to demonstrated that the education of Yukon students had improved. As Minister of Education, he also oversaw and approved the decision to replace the F.H. Collins High School in Whitehorse, a decision that eventually went millions over budget and resulted in a half decade of delays. In Cabinet, Rouble also briefly held the portfolio overseeing the Yukon Public Service Commission from 2008 to 2010. He was appointed Minister of Energy, Mines and Resources in February 2010 when Yukon Party Cabinet minister Brad Cathers temporarily quit the Yukon Party in protest over Premier Fentie's leadership. Rouble held the position of Minister of Energy, Mines and Resources until the end of that term. In 2011, Rouble announced that he would not seek re-election in the 2011 Yukon election, choosing instead to pursue a doctorate degree in education. His surprise departure led to media speculation that he was unhappy with the resulting change in the leadership within the Yukon Party. Rouble had refused to state who he would support in the leadership race to replace Dennis Fentie, but it was thought he harbored his own leadership ambitions.
After retiring from politics, Rouble was appointed by Premier Pasloski as the Chair of the Yukon Land Use Planning Council, the body under the Yukon's Umbrella Final Agreement responsible for making recommendations to the Yukon Government on land use planning. The appointment drew disdain from the opposition and the media, since as Minister of Energy, Mines and Resources, Rouble had worked to undermine the recommendations of the Council's Peel Watershed Commission after six years of public consultations. There was concern that Rouble prejudiced the independent mandate of the Council and could weaken government relations with First Nations. Both the Yukon News and members of the opposition called upon Rouble to recuse himself of the appointment, which he did not. The process surrounding the Peel Watershed Commission eventually led to a legal challenge at the Supreme Court of Canada in 2017.
