Michelle Wu, a Democrat, served as a member of the Boston City Council from January 2014 until becoming mayor of Boston in November 2021. Wu was first elected to the City Council in November 2013, and was re-elected three times (in 2015, 2017, and 2019). In 2016 and 2017, Wu served as the council's president.

Wu received positive recognition for her work as a city councilor. Wu served on the Council at a time when the body acted to wield greater influence than earlier iterations had in preceding decades. The council acted particularly bolder during her own tenure as its president. Wu was considered to be a progressive member. As a councilor, Wu authored several ordinances that were enacted as law. This included an ordinance to prevent the city from contracting with health insurers that discriminate in their coverage against transgender individuals. She also authored enacted ordinances to have the city protect wetlands, support adaption to climate change, enact a plastic bag ban, adopt Community Choice Aggregation, and provide paid parental leave to municipal employees. As a city councilor, Wu also partook in a successful effort to adopt regulations on short-term rentals.

Elections Wu was first elected to the Boston City Council in 2013, and was subsequently thrice reelected. In 2021, Wu decided not to seek a fifth term on the City Council and to run for mayor instead.

2013

Wu was first elected to an at-large seat on the Boston City Council in November 2013. She finished in second place to incumbent Ayanna Pressley in an election where the top four finishers were elected to at-large seats.

Adrian Walker of The Boston Globe observed early into Wu's campaign that her candidacy that her entry into the City Council election was generating excitement in a municipal election cycle that had yet to foster much other excitement despite a rare open-seat race for mayor.

In August 2013, an article by Emily Cahn of Roll Call noted Wu had already made a strong impression on political observers in Boston, and that Wu was being speculated as a potential future candidate for the United States House of Representatives. The article quoted an unnamed Democratic political consultant as remarking, "She is one to watch. She’s running for the Boston City Council for the first time, but everybody is so impressed with her."

Wu received the endorsement of The Boston Globe'''s editorial board. In endorsing Wu's candidacy, the editorial board wrote, The Boston Globe editorial board further praised Wu's work on reforming restaurant permitting and licensing during her time in the mayoral administration of Thomas Menino. The editorial board observed that Wu's candidacy had received support from some prominent political players in part due to Wu's work as a staffer for Elizabeth Warren's successful 2012 Senate election campaign.

In a 2021 article, Ellen Barry of The New York Times observed that Wu's temperament and personality as a candidate contrasted with that conventionally associated with Boston politicians, as did the fact that she was not a Boston native,

Barry further observed that Wu's candidacy came as the city "was turning a corner" with an "increasingly young, well-educated, and left-leaning" electorate. Shortly before the day of the general election, Wu experienced laryngitis. Supporters of her campaign worried that her inability to deliver speeches in the closing stretch of the election might impair her performance in the election. However, she nevertheless prevailed in the election result. Barry observed,

2015 Wu was re-elected in November 2015, again coming in second behind to Pressley. Wu was again endorsed by the editorial board of The Boston Globe.

2017 Wu was re-elected to a third term on the council in November 2017, garnering the most votes among all at-large candidates; her tally of over 65,000 votes was the most since Michael J. McCormack in November 1983. Wu was again endorsed by the editorial board of The Boston Globe.

2019 Wu re-elected to a fourth term in November 2019, again placing first. In her 2019 campaign, Wu shared a campaign office with Kim Janey, who was seeking reelection as a district city councilor, and fellow at-large city council candidate Alejandra St. Guillen. Sharing campaign resources with a fellow at-large candidate was regarded as an unusual move that reflected confidence by Wu in her own odds of securing reelection. Wu was endorsed by Attorney General Maura Healey and the editorial board of The Boston Globe.

Council politics Wu was the first Asian American woman to serve on the council, and only the second Asian American member to serve on the council. In late 2014, Wu became the first city councilor in Boston history to give birth while serving on the Boston City Council. From January 2016 to January 2018, she served as president of the council, the first woman of color and first Asian American to hold the role. Wu's council presidency made her only the third female president in the then-106 year history of the Boston City Council. In 2024, Wu recalled the atmosphere on council at the start of her tenure as being, "so gendered and racialized and pitted." When she joined the council, she and Ayanna Pressley were the only two women of color serving on the council. However, at the end of her tenure six of the council's thirteen members were women of color.

During her tenure on the Boston City Council, Wu chaired the Post Audit; Planning, Development and Transportation; and Oversight committees.

While Boston's strong mayor form of government had conventionally limited the impact that members of the council had on the city government, Wu's tenure on the City Council occurred during a period in which the council began to increasingly wield its power, with the body yielding less to the mayor than previous iterations of the council had in the preceding decades and making use of its subpoena powers for the first time in decades. Wu was regarded as a progressive on the Boston City Council, and the council began pushing its politics in a similar direction during this time. In December 2019, Milton J. Valencia of The Boston Globe opined that, beginning under Wu's tenure as council president and continuing into Andrea Campbell's tenure as her successor, the Boston City Council, "has been, perhaps, the most aggressive in recent history in pushing reforms, often to the left of the mayor, on issues addressing climate change and economic and racial equity."

In April 2019, Rachael Allen of The Atlantic wrote that Wu, "embodies the kind of political change that’s making waves in Washington, D.C., and cities across the country." Allen described Wu as presenting a unique leadership style when compared to other rising politicians that challenged the status quo, writing,

A member of the council's liberal/progressive wing, Wu often cast votes that aligned with other progressives on the council. Other members of the informal liberal/progressive grouping on the council included Ayanna Pressley and Lydia Edwards.

Wu would occasionally voice her policy disagreements with Mayor Walsh, either on social media or when speaking to the press. Mayor Walsh grew frustrated by this, and criticized her for not keeping her disagreements with him more private.

Support for Bill Linehan's 2014 council president candidacy In the weeks prior to taking office for her first term, Wu announced that she would vote for Bill Linehan to serve as the president of the Boston City Council. Many of Wu's progressive backers were surprised, since Linehan was seen as the council's most conservative member. At the time, she faced backlash from many progressives for this. Many of the city's liberal voters were strongly opposed to the idea of Linehan becoming council president, and a number of liberal activists threatened that Wu would lose re-election in 2015 if she did not change her mind. The Boston Globe's editorial board later characterized the matter as causing a "controversial start" to Wu's tenure, having "enraged some of the liberal voters who supported her."

In addition to Linehan, councilors Matt O'Malley and Tito Jackson had also been seeking to become the next council president. Both O'Malley and Jackson were considered to be members of the council's liberal wing (which had five returning members, including the two of them). There was an open agreement between O'Malley and Jackson that if one of them faltered in their efforts to secure support, they would bow out in favor of the other thus ensuring that one of them or the other could receive the votes of all five returning liberal members. Meanwhile, Linehan was regarded as all-but-sure to win the backing from the six returning council members (including himself) who were not part of the council's liberal wing. This meant that the council presidency election had only two likely swing-votes: Wu and the only other newly elected member: Timothy McCarthy. O'Malley had appeared close to prevailing for a period, securing pledges of support from all returning liberal members as well as from McCarthy. This however, left him one shy of a majority. Despite being aligned with the council's liberal wing, Wu had not followed the rest of that wing in pledging her support to his candidacy. O'Malley lost ground after McCarthy withdrew his backing from him and instead gave his support to Linehan, giving Linehan majority support. Soon after this, Linehan bolstered his majority support by also garnering Wu's backing.

Wu justified her backing of Linehan's bid for the council presidency by citing her belief that Linehan would be the most effective at running the City Council, and by citing her support for Linehan's promises to decentralize power away from the City Council president's office, empower the council's committee chairs, and reorganize the central staff of the City Council. The editorial board of The Boston Globe wrote that Wu's support for Linehan's bid for the council presidency was "a head-scratcher, at the very least," and called the rationale that Wu gave for her vote as, "honest enough but politically naïve." Andrew Ryan of The Boston Globe later observed, "Wu played a crucial role [in Linehan's election as council president], casting her vote for him despite pressure from liberal supporters."

After O'Malley had failed to cobble together the support of a majority and Linehan had, Jackson attempted again in earnest to secure himself backing, but failed to peel away supporters from Linehan. Pressley followed, with Linehan defeating her last-minute candidacy. The Council ultimately elected Linehan as its president by a 8–5 vote, with Linehan defeating a last-hour challenge from Ayanna Pressley.Multiple sources:

2016 election as council president After her 2015 reelection to a second term, Wu sought support from other councilors for her election as council president in the 2016–17 council term. Her bid for the council presidency was supported by outgoing council president Linehan, and on November 13, Wu had publicly announced that she had received pledges of support from a majority of council members. At this point, Wu's support came roughly from the same grouping of members that had elected Linehan to the council presidency, and despite her own progressive leanings included key support from members of the council's conservative bloc. Many of council's liberal members had initially supported Matt O'Malley instead of Wu. Mark Ciommo also sought to secure support for himself, but withdrew. On the eve of the vote, O'Malley too withdrew, voicing his support for Wu. On January 4, 2016, Wu was unanimously elected council president. Council rules prevent the presidency from being held by the same member for multiple terms consecutively, and Andrea Campbell was elected in January 2018 to succeed Wu.

Support for Kim Janey's 2020 council president candidacy