Michelle Mungall was born and raised in St. Albert, Alberta. She graduated from Paul Kane High School in 1996 and then attended the University of Alberta in Edmonton. She majored in political science and graduated with honours in 2001. At her university she organized a group named the Preservation of Education Accessibility for Society which sought public funding for post-secondary education. She grew up in a household that debated politics, and in which her parents favoured the Progressive Conservative Party, but she became involved with the New Democratic Party during her first year of university. During her final year, she became the NDP candidate in the St. Albert riding during the 2001 Alberta general election. Mungall was an underdog, the race was expected to be close between the incumbent Progressive Conservative Mary O'Neill and the Liberal challenger Len Bracko. Also in 2001 she worked as a youth organizer for the Northern Alberta Alliance on Race Relations and was profiled in the Edmonton Journal as one of Alberta's 30 most-promising people under 30 years old.
In 2001 Mungall re-located to Nelson, British Columbia. She quickly integrated into the community and ran for city council in the November 2002 election. She was identified as a wildcard in the race, not expected to win because of her inexperience and being new to Nelson, but expected to do well as she ran a very strong campaign. She finished third, gaining her one of the six council seats.
At the age of 24, she was the youngest councillor in Nelson's history and was the youngest female municipal council member in Canada at the time. She was appointed to several committees, including the Youth Centre Committee, the Nelson Electric Tramway, and the Social Advocacy Committee, and task forces, including the Participatory Governance Task Force, Arts, Culture and Heritage Task Force, and the Solid Waste Management Task Force. As part of that Solid Waste Management Task Force, she helped introduce a blue box recycling program and privatized commercial garbage pick-up. She introduced an anti-war resolution, which the council adopted, matching similar resolutions adopted in several other BC municipalities. On local issues, she supported moving city hall to the White Building in a vote that split the council but was adopted. In another split vote which was ultimately adopted, Mungall supported directing $30,000 in 2005 towards arts and culture initiatives. She was on council during the 2004 ten-week lock-out of municipal union workers as contract negotiations stalled over the issue of staffing levels.
During most of the time she was on council, she also worked at the Nelson Food Coalition. She opted not to stand for re-election in the 2005 municipal election, citing a desire to further her education. After completing an eight-month contract as a community developer with the Nelson Committee On Homelessness, she traveled to Africa to spend seven months as an intern in Lusaka, Zambia working as a National Programmes Assistant for the World Young Women's Christian Association. Upon her return, she began studying her Master's in Royal Roads University's Human Security and Peacebuilding program.
She returned to Nelson in February 2007 and worked first at the Nelson and District Youth Employment Resources Center, then at a microfinace organization called the Circle of Habondia Lending Society. At the same time, she was writing her Master's thesis regarding homelessness in rural British Columbia. She submitted her dissertation in March 2009 and was awarded a Master of Arts degree by Royal Roads University. Mungall married Zak Matieschyn on July 23, 2011 in Kokanee Creek Provincial Park.
In 2008, after Nelson-Creston Member of the Legislative Assembly Corky Evans announced he would not seek re-election, Mungall entered the race for the BC NDP nomination. Three other women contested the nomination: fellow Nelson residents Kim Adamson and Bev LaPointe, as well as Creston small business owner Rhonda Barter. The nomination vote was held in February 2009. In the preferential vote Lapointe and Barter were eliminated in the first two rounds and in the third round Mungall narrowly defeated Adamson. Campaigning for the 2009 election began soon afterwards. She faced three other candidates, but only the BC Liberal candidate, long time rural director at the Regional District of Central Kootenay and former chair of the Columbia Basin Trust Josh Smienk was considered to be a serious challenger to Mungall. The other candidates, Sean Kubara of Kaslo running for the Green Party and David Duncan of the BC Conservative Party ran limited or no campaigns. Mungall campaign focused on issues surrounding the local economy, independent power producers, and health care. She took 54% of the vote in winning the riding, but her New Democratic Party lost provincially to the BC Liberals who formed a majority government.
In the 39th Parliament, with the New Democrats as the Official Opposition, party leader Carole James assigned Mungall the role of deputy critic to Dawn Black on Advanced Education, where Moira Stilwell was the minister. As deputy critic, she spoke out against the June–July 2009 cuts to student aid programs and supported the student union of Selkirk College during a Halloween 2009 public event to highlight student loan problems.
In 2009, Mungall along with her BCNDP colleagues, community groups and city councillors, put the pressure on the Liberals to back down from planned cuts to funding for programs for survivors of domestic violence. "Literally minutes before Mungall was to speak at a Tuesday news converence, Heed's office dropped a press release saying the government was backing away from the $440,00 cut to programs for family-violence victoms - mainly battered, abused and fearful women and children."
On local issues, Mungall hosted a public meeting on the controversial Glacier-Howser hydroelectric project which was undergoing environmental assessment, which she would later oppose, she delivered a 3,000 signature petition to the legislature advocating for improvements to the Kootenay Lake Hospital and hired an intern from the University of British Columbia to research food security in the Kootenays. Mungall was a vocal opponent to the proposed Jumbo Glacier Ski Resort and together with her BCNDP colleagues questioned the government on their creation of a town with no population.
She was selected for the Select Standing Committee on Finance and Government Services in the first and second sessions which engaged in budget consultations across the province. She also spent time as chair of the NDP's Women's Caucus which monitored women's issues In December 2009-January 2010, she and her husband visited Cambodia and participated (at the request of Mu Sochua) in training of local women who were preparing for an upcoming election
In the run up to the 2011 BC NDP leadership election Mungall supported Adrian Dix, who would eventually win the leadership post. As the third session of the 39th Parliament began, Dix appointed her critic for advanced education and for youth and was assigned to the Select Standing Committee on Education.
In November 2011, Mungall introduced her first piece of legislation, a private members bill entitled the Private Career Training Institutions Amendment Act. The bill would have required more rigorous reporting and complaint resolution requirements in private educational institutes and brought English as a foreign or second language schools under the Private Career and Training Institutions Act.
In the 2013 election Mungall was re-elected MLA for Nelson-Creston. She received more votes than her opponents, the Liberal's Greg Garbula and Green's Sjeng Derkx combined. Following the election, Mungall was named Social Development Spokesperson in the official opposition shadow cabinet. She has also taken on the role of Opposition Deputy House Leader and from 2013 to 2014 was the Chair of the Opposition Social Policy Committee.
In 2014 Mungall championed a highly publicized and ultimately successful campaign to end the BC Government practice of clawing back child support payments from single parents receiving social assistance or disability payments. In response to the efforts of Mungall and anti-poverty advocates across the province, the BC government announced it was ending the child support clawback as a part of their February 2015 budget.
In 2015, Mungall successfully took on another Liberal clawback, this time one that took away EI maternity benefits from families on income assistance.
The 2016 Liberal budget included changes to the subsidized bus pass program for people with disabilities. It effectively increased the cost of a bus pass from $45 per year to $52 per month, a total of $624 per year. Mungall fought alongside advocates for people with disabilities to raise the rates and keep the bus pass program and the government responded. In June 2016 the government announced it would remove the $45 annual fee for a disability bus pass and the 2017 budget included a $50 per month increase in disability rates. Mungall publicly noted that the increase was approximately the same as the previous years increase in cost for the disability bus pass.
Through the 40th Parliament, Mungall continued to speak out against the development of the Jumbo Glacier ski resort. In a 2014 Vancouver Sun article she states "I think they just need to end this farce and acknowledge that it hasn’t been substantially started. It’s nothing but a concrete slab. It’s very close if not in an avalanche path. It’s not safe and nobody in the region wants it. End it." Mungall presented a petition with 61,526 signatures to keep Jumbo wild in the BC Legislature in March 2017.
In May 2014 she introduced a private members bill, the Poverty Reduction and Economic Inclusion Act (Bill M-212). The bill aimed to target the root causes of poverty and mandate the development of a comprehensive poverty reduction strategy. Mungall and her colleagues have introduced this legislation six times, and each time it died on the order paper and did not make it to second reading. BC continues to be the only province in Canada without a poverty reduction plan.
On July 18, 2017, Mungall was sworn in as BC Minister of Energy, Mines & Petroleum Resources.