He had won the Democratic primary election over a field of five other candidates, including former U.S. representative Gwen Graham and former Miami Beach mayor Philip Levine.

In 2022, Gillum was indicted on 21 felony counts, including wire fraud, conspiracy, and making false statements, for allegedly diverting money raised during the campaign to a company controlled by one of his top advisors.

The joint body of city and county commissioners, known as the Capital Region Transportation Planning Agency, elected him to serve as their chairperson for a year (January 2005 through December 2005).

[9] The Digital Harmony Project is an initiative championed by Gillum with support from the City of Tallahassee, local businesses and technology partnerships.

Digital Harmony won the Significant Achievement Award in the Web & e-Government Services category from the Public Technology Institute.

For the first two years, it provided every incoming Nims Middle School sixth and seventh-grader with a new desktop computer, free internet access and online academic curriculum training on core subjects.

[22] On February 17, 2015, Gillum welcomed United States secretary of transportation Anthony Foxx to Tallahassee to kick off the Grow America Express Tour.

[23] Gillum also contributed to the DOT Fastlane Blog, in which he stressed the importance of long-term transportation investments for America's mid-size cities.

[25] Also in March 2015, Gillum participated in a conference call with other Florida mayors and United States deputy secretary of commerce, Bruce Andrews; a call in which Gillum stated his support for Congress to pass trade promotion legislation that would bolster international trade, and stressed the importance for local governments of a leveled playing field.

[26] On March 27, 2015, Gillum held the Mayor's Summit on Children,[27] a large conference in which business and community leaders came together to learn about the importance of investments in quality Early Childhood Education (ECE).

[28] Speakers included Dr. Craig Ramey, research scholar of human development at Virginia Tech, who spoke about the importance of ECE to language development and the vocabulary gap that can form between those who receive quality ECE and those who do not; and Rob Grunewald, economist at the Federal Reserve Bank of Minneapolis, who spoke about the importance of early learning to the long-term economic success of a community.

[31] Also in May 2015, Gillum, in partnership with several local and national organizations, orchestrated the Tallahassee Future Leaders Academy (TFLA), a summer jobs program which employed over 100 youths throughout city government.

[33] In response to an increase in shootings, Gillum and the Tallahassee Police Department worked with community organizations to implement Operation Safe Neighborhoods in 2015.

[38] An investigation into the emails started after Paul Henry, a retired state trooper from Monticello, wrote State Attorney Jack Campbell in March to allege Gillum committed grand theft and official misconduct by paying for the software with city funds when he believed they served no public purpose.

[39] In August 2017, a Leon County grand jury declined to indict Gillum personally due to lack of evidence of criminal wrongdoing.

[39] During his mayoral campaign in 2014, Gillum faced allegations of misconduct after hiring private equity investor Adam Corey as the treasurer.

Corey is an investor in The Edison, a restaurant that received taxpayer money from the city to help with the Cascades Park development project.

[44][45] Gillum won the Democratic nomination for governor in an upset victory over the expected winner, former congresswoman Gwen Graham, 34–31%.

"[50] This “disastrous gaffe” was discussed by Dexter Filkins in The New Yorker:[51] DeSantis insisted that there was no racial motive behind the statement—"He uses a lot of dorky phrases like that," one of his former colleagues told me—and the outrage didn't endure.

[63][64] He opposed the Trump administration's decision to withdraw from the Paris Agreement, and said that he would as Florida governor work with other states in a state-based climate alliance.

[59] Gillum is in favor of a 2018 ballot proposition, Amendment 4, to restore the voting rights of most individuals who have completed felony convictions.

"[67] On June 22, 2022, Gillum was indicted by the U.S. Attorney's Office in the Northern District of Florida on 21 felony counts, including wire fraud, conspiracy, and making false statements for allegedly diverting money raised during the campaign to a company controlled by Sharon Lettman-Hicks, one of his top advisors on his campaign, who then used the money to pay Gillum.

While attending FAMU, Gillum was recognized by the National Center for Policy Alternatives in Washington, D.C., as the country's top student leader in 2001.

[80] In March 2020, the Tallahassee Democrat reported that Gillum was one of three men, one of whom was experiencing a drug overdose, who were found by police with "plastic baggies of suspected crystal meth" in a hotel room in Miami Beach.

[81] On March 16, Gillum stated that he would enter rehabilitation, citing struggles with alcohol and depression after narrowly losing the 2018 Florida gubernatorial race.