After graduating from Ohio State in 2000, he earned a Juris Doctor from the Case Western Reserve University School of Law.

[10][11] Faced with opposition from fellow council members, Mandel introduced and advocated for a 2 mill property tax rollback, which would have saved the average homeowner $100 a year on a home valued at $160,000.

[31] During Mandel's time as treasurer, Ohio retained the highest possible rating from Standard & Poor's for the state's $4 billion government investment fund.

"[37] Because there was no coordination with a similar effort undertaken by then-Governor John Kasich, Ohio ran two overlapping disclosure sites for several years.

[50] Mandel was the Republican nominee to challenge Democratic incumbent Sherrod Brown in the 2012 election for U.S. Senate from Ohio.

[53] Mandel earned the endorsement of several prominent conservative politicians, including New Jersey Governor Chris Christie, Florida Sen. Marco Rubio, and Sen. John McCain.

[55] Mandel's campaign was singled out by the independent fact-checking group PolitiFact for its "casual relationship with the truth" and its tendency to "double down" after inaccuracies were pointed out.

PolitiFact wrote: "For all the gifts Mandel has, from his compelling personal narrative as an Iraq war veteran to a well-oiled fundraising machine, whoppers are fast becoming a calling card of his candidacy.

As of July 2012, these outside groups—including Crossroads GPS—aired $10 million in TV advertising supporting Mandel and attacking Brown, outspending Democratic Party-aligned outside groups by a margin of more than five-to-one.

[58] Mandel's campaign was aided by over $1 million spent primarily on attack ads by a 501(c)(4) organization called the "Government Integrity Fund".

[63] In late 2016, a Super PAC called Ohio Freedom Fund was created to support Mandel's Senate bid.

As of April 2017, the Ohio Freedom Fund's primary contributor is Citizens for a Working America, a nonprofit organization not subject to campaign finance disclosures.

At the time that the Ohio Freedom Fund Super PAC was created, Mandel, in his capacity as state treasurer, was appearing in a series of advertisements promoting a new investment program for families with special needs children.

[64][65] In July 2017, Mandel stated his support for alt-right activists and conspiracy theorists Mike Cernovich and Jack Posobiec after they were criticized in an Anti-Defamation League (ADL) report.

"[66] Mandel dropped out of the race on January 5, 2018, citing the need to spend more time with his family relating to his wife's health issues.

[70][71] Declaring his candidacy, Mandel touted his support for President Donald Trump, although he had initially endorsed Marco Rubio for the party's nomination in the 2016 presidential election[72] and voted for him in that year's Ohio Republican primary.

[73] In March 2021, Mandel was suspended from Twitter for 12 hours for creating a poll about which type of "illegals" would commit more crimes, "Muslim Terrorists" or "Mexican Gangbangers".

[75][76] In October 2021, posting on a far-right conservative website, Mandel claimed that Jewish financier George Soros and the "deep state" were responsible for the COVID-19 pandemic, the Black Lives Matter movement, antifa, and the January 6, 2021 assault on Capitol Hill.

[88] In a campaign advertisement during his 2012 Senatorial run, Mandel claimed opponent Sherrod Brown "cast the deciding vote on the government takeover of health care".

[90] Mandel has called for what he terms as "aggressive and responsible" energy exploration that protects "the air we breathe and water we drink" while reducing environmental regulation.

[87] In 2012, Mandel said that he disagreed with plans to set a "date certain" for withdrawal of U.S. military forces from Iraq and Afghanistan, also stating, "at some point in time, we have to take the training wheels off and we have to allow those countries to stand on their own two feet.

"[96] In early September 2021, when the U.S. evacuated Afghan allies from Afghanistan, Mandel said that refugees were being brought to "the heart of America ... To protect our kids, our communities and our Judeo-Christian way of life, we must FIGHT this with all our might.

The divorce was finalized in June 2020 and all records were sealed until 2021 when details regarding finances, custody of their three children, and child support were released.

[100][101] Their divorce was re-opened in 2023 over disputes regarding child support, Mandel's failure to pay for the children's healthcare, and numerous other issues.

However, they were given the option to avoid jail time by resolving issues with a 529 college savings account and their children's sports and medical expenses.