Janey began her career as a community organizer and education advocate, working for groups such as Parents United for Child Care.

Being the incumbent City Council president, she became the acting mayor of Boston upon Marty Walsh's departure from the post when he resigned after being confirmed as the United States secretary of labor.

She signed into law an ordinance which restricted the Boston Police Department's use of tear gas, pepper spray and rubber bullets, a measure in the line of which had been vetoed earlier in the year by Mayor Walsh.

This laid groundwork that her successor, Michelle Wu, built upon to launch an expanded fare-free bus service pilot program.

Since May 2022, Janey has served as the chief executive officer of Economic Mobility Pathways (EMPath), a Boston nonprofit which addresses poverty.

[7] The birthplaces of her ancestors include North Carolina on her mother's side, and Guyana, Virginia, Nova Scotia, and Massachusetts on her father's.

[24][9] She dubbed her district "ground zero" for issues in the city such as economic and racial inequalities, an insufficient supply affordable housing, traffic, and the opioid epidemic.

In promotion of the proposed legislation, she said, "While chain stores also play a role in our economy, it is imperative that community members have the opportunity to weigh in on whether to allow them based on the unique circumstances of their neighborhood business district.

[10] In late February, she designated several key individuals that she would appoint as members of her senior leadership team once she assumed the role of acting mayor.

Ahead of assuming the position of acting mayor, Janey selected Omar Boukili to serve as her senior advisor on COVID-19 response and strategic initiatives.

[67] Despite calls by her mayoral election opponents Andrea Campbell and Michelle Wu to do so in August, amid rising delta variant infections, Janey opted not to implement a COVID-19 vaccine requirement for entrance to indoor establishments, such as restaurants and gyms.

[68][65][69] In late March, Janey's administration temporarily shut down the city's "comfort station" in the Mass and Cass area (also known as the "Methadone Mile"), which is the location of a large homeless population.

[72] In September, Janey announced plans to house homeless people from the Mass and Cass area at a hotel in Revere, Massachusetts.

[77] She signed an executive order creating a "central coordinating team" of local and state officials to outline shelter and addiction treatments available in the region for those needing them.

[83] However, weeks later, Governor Charlie Baker threatened that state officials would reject Janey's withdrawal, unless the city submitted a replacement plan.

[85] During Janey's mayoralty, the city began to explore the possibility of creating a climate bank through the Boston Green Ribbon Commission public-private partnership.

[82][86] In April, Janey named Stephanie Everett to be head of the city's new Office of Police Accountability and Transparency,[87] which was created in accordance with an ordinance that Walsh had signed into law earlier that year.

[88] In May, Janey signed into law an ordinance which restricted the Boston Police Department's use of tear gas, pepper spray and rubber bullets.

[89] Around the same time, she announced that she had directed the city to drop its legal defense of a Boston Police Department promotion exam that had been criticized by opponents as "racially discriminatory".

[113] In June, two female Latina American Boston School Committee members resigned over a scandal involving racially-charged text messages that they had sent about White West Roxbury residents.

[121] As mayor, Janey's successor Michelle Wu would subsequently pursue a litigation against the United States Census Bureau on these grounds.

However, Ellen Barry of The New York Times and Lisa Kashinsky of Politico have suggested that her comments in early August on vaccine passports were damaging to her momentum.

[125][128] By the closing weeks of the nonpartisan primary election campaign, Michelle Wu was seen as the front-runner, with Janey being perceived as competing with Andrea Campbell and Annissa Essaibi George for a second-place finish.

[126] In late-August, Joe Battenfeld of the Boston Herald characterized her as having run a "Rose Garden campaign", emphasizing her acting incumbency through weekly press conferences and playing a visible role in the city's response to the COVID-19 pandemic.

[132] Vennochi argued that, unlike Menino, Janey had been cautious in governing, and, "didn't define herself or her plans for a future administration", and had been "carefully scripted" in press conferences, outside of her controversial off-hand remarks about vaccine passports.

[126] In contrast, two of her opponents, Michelle Wu and Annissa Essaibi George, had been elected city-wide in the past as at-large city councilors.

[142] On September 24, Janey met with mayoral general election candidates Annissa Essaibi George and Michelle Wu at the Francis Parkman House, and the three agreed to November 16 as the tentative date for the expected transition of power for the mayoralty.

[81][147] In late-May 2022, Janey was announced as the next chief executive officer of the Boston Economic Mobility Pathways (EMPath), a nonprofit focused on addressing poverty.

She was tasked to work with the foundation's president and chief executive officer, M. Lee Pelton, on a project related to documenting, preserving, and promoting awareness of historical landmarks located in neighborhoods of Boston with large populations of people of color.

[156] In January 2024, Janey was a member of a coalition of groups and individuals that filed a challenge to Donald Trump's inclusion on the presidential ballot in Massachusetts.