Mitchell was sworn in during a ceremony Friday at the legislature replete with red carpets, a brass band, a military guard of honour and a 15-gun military salute.
"In my wildest dreams I could not have imagined my life's path leading to this moment," Mitchell, sitting in the ornate, high-backed mahogany Speaker's chair, told the assembled dignitaries in the legislature chamber.
"I am humbled by this rare opportunity to represent Her Majesty the Queen and to serve as a safeguard of everything that the Crown in Canada represents."
Mitchell is the province's 18th lieutenant-governor, and replaces Don Ethell.
The lieutenant-governor is the Queen's representative in the province, and carries out ceremonial duties, including signing legislation. She will also play host to visiting dignitaries.
Past lieutenants-governor have, while in office, worked to raise awareness of issues or causes.
Mitchell told reporters she wants to raise the profile of the work of police officers, and also boost the Special Olympics.
"There is a great kind of need to help support the Special Olympics," Mitchell told reporters after the ceremony. "(It's my) hope that every single sports team might consider having a Special Olympian with them. They do that at (University of Calgary) on the basketball team and it's been very inspirational."
Mitchell is the senior partner and the founder of an international marketing and consulting firm. She is the past president of the Calgary Chamber of Commerce and former vice-chair of the Global Business Forum.
Sports is a key thread that runs through many of her philanthropic works, which include stints as a director for Hockey Canada Foundation and governor of the Canadian Women's Hockey League.
She served as a board member for the inaugural World Women’s Under-18 Hockey Championships
She recalled meeting and being inspired by Canadian national team player Hayley Wickenheiser.
"Especially when women get a chance to play on a team, they are excellent, excellent at everything they do," said Mitchell. "When you're lying there on the ice, you have to get up fast. Well life is about all those things that hit us and learning how to get up and keep going."
Mitchell won the Alberta Centennial Medal in 2005 and became a member of the Order of Canada in 2012. Her husband is lawyer and former CFL commissioner Doug Mitchell.
Premier Rachel Notley paid tribute to Mitchell at the ceremony.
"She has been relentless about putting her time and her talents to work for worthy organizations," said Notley. "She has opened doors for people who might otherwise have found them shut."
The ceremony had one moment of concern when the guard flanking Mitchell fainted, crashing into a flag stand. He was later reported to be OK.
On Monday, Mitchell will be back in the legislature chamber to read the throne speech outlining the government's goals to begin a new session of the legislature.