Originally from Regina, Wagantall was raised in southern Saskatchewan until she moved with her parents and six siblings to Esterhazy in 1967.

On full scholarship, she completed three of four years of her Bachelor of Science in Physical Education with top honours at the University of Saskatchewan. During her summers, she worked in hospitals and level 4 care homes.

After traveling the world for a couple of years, Wagantall and her husband entered into a partnership in a lumberyard and contracting business in Springside. They eventually bought out the other partners, then lost their business during the early 1980s recession.

Wagantall moved to Edmonton in 1985. She served as the athletic director for what was then North American Baptist College (later Taylor College and Seminary).

In 1991, their family moved to Lloydminster, Alberta where her husband was a pastor in NewLife Community Church for seven years. During that time Wagantall coached community, junior and senior high basketball and worked as a teacher's assistant with special needs children in kindergarten and high school.

Upon returning to Edmonton in 1998, Wagantall worked for ten years at Taylor University College and Seminary in development, accounting and student loans. She also worked as a Sunday School teacher.

In 2004 Wagantall served on the Conservative Party of Canada Board of Directors for Edmonton-Mill Woods-Beaumont as the election readiness chair, president and financial agent. She door-knocked with then-candidate Tim Uppal against incumbent David Kilgour, and served as campaign manager for Mike Lake in 2006 and 2008. She served official agent for Tim Uppal in 2011. She worked in Uppal's Edmonton-Sherwood Park constituency office until March 2011, when she and her husband returned home to Esterhazy to own and operate Positive Signs, a sign and print company.^[1][2]

In November 2014, Wagantall won the Conservative nomination in Yorkton—Melville for the 2015 federal election.^[3] On October 19, 2015, she won the seat with 59.2% of the vote.^[4][5] In the 42nd Parliament Wagantall introduced one private member bill, Bill C-225 titled Protection of Pregnant Women and Their Preborn Children Act (Cassie and Molly's Law), which sought to add a new class of person, a "preborn child", into the Criminal Code and make injuring or causing death to the preborn child while committing or attempting to commit another offence against a female person that the person knows is pregnant to be a separate offense.^[6] While the bill was similar to Ken Epp's Unborn Victims of Crime Act, Bill C-485, which received second reading and referral to committee in March 2008 during the 39th Parliament, Wagantall's Bill C-225 was defeated in a vote in October 2016^[7] with only members of the Conservative Party voting in favour.^[8]

Wagantall was re-elected in the 2019 election. During the ensuing 43rd Canadian Parliament, she introduced one private member bill, Bill C-233, An Act to amend the Criminal Code (sex-selective abortion) which sought to create a new offense within the Criminal Code, punishable by up to 5 years imprisonment, applicable to medical practitioners who perform an abortion based solely on the grounds of the child's genetic sex. It was brought to a vote on June 2, 2021, but defeated with only Conservatives Party members voting in favour.^[9][10] In the 2020 Conservative Party of Canada leadership election she endorsed Leslyn Lewis.^[11]

After the House of Commons introduced a vaccine mandate, Wagantall claimed a medical exemption. It was rejected and she attended House meetings virtually.^[12]

She was re-elected in the 2021 election. During the campaign, her campaign manager organized an online petition against mask mandates in Yorkton's Good Spirit School Division and Christ the Teacher Catholic Schools. She also ran a Facebook page on the topic.^[13][14]

During the "Freedom Convoy" protests in Ottawa, Wagantall shared an unfounded claim that Prime Minister Justin Trudeau's official photographer, Adam Scotti, had been sent to the protest to photograph a man with a Confederate flag. Wagantall claimed that this was to "misrepresent thousands of law-abiding, hard-working Canadian truckers and millions across the nation supporting them." She later deleted the Facebook post, and refused to comment on the matter.^[15]

Wagantall has been married to H. Martin Wagantall since 1976. She has three grown children and nine grandchildren.^{[citation needed]}

Wagantall is a Christian.

• Cathay Wagantall – Parliament of Canada biography