From 1983 to 1985, she worked as a commissioner for the Harford County District Court,[1] afterwards unsuccessfully running for the Bel Air Town Commission.

[7] In January 1990, following the resignation of John W. Hardwicke from the Harford County Council, McComas applied to serve the remainder of his term.

The Harford County Republican Central Committee voted to nominate her, Barry Glassman, and Jeffrey Wilson to the seat.

[10] She ran on a platform involving transportation, crime, and development issues, and faced challengers Robert Shaffner and Francis Eurice in the Republican primary election,[11][12] which she won with 50.1 percent of the vote.

In the general election, McComas faced Bel Air town commissioner David E. Carey,[13] whom she defeated with 61.4 percent of the vote.

[2] In January 2010, McComas suffered a heart attack while visiting her mother, who died a few hours after the incident, in Wyoming.

[28] In February 2022, McComas opposed a bill to repeal a law that allowed police to arrest children for disturbing school activities.

During debate on the bill in the House, she remarked that "I've been accused of implicit bias because I said, you know, that Black fathers aren't as prevalent as they were in the 40s and 50s.

Her comments drew anger from other House lawmakers and prompted the bill's sponsor, Jazz Lewis, to issue a statement calling on McComas to immediately apologize for her remarks.

[30] During the 2023 legislative session, McComas supported the SERVE Act, a bill introduced by Governor Wes Moore to establish a service year option for high school graduates.

[34] In the legislature, McComas has voted against bills to raise the state minimum wage, which she says hurt small businesses.

[51] In 2005, McComas introduced legislation that would allow town police officers to cross jurisdictional borders to pursue drunk or reckless drivers.

[52] In October 2020, following the murder of George Floyd, McComas said that she did not support banning police chokeholds, saying that the idea gave her "heartburn" and preferring instead to discourage their use.

[55] In April 2010, McComas voted against an impeachment resolution against Maryland Attorney General Doug Gansler for issuing an opinion supporting same-sex marriage.

[57] In 2013, McComas opposed a bill to repeal the death penalty in Maryland, saying that it would make people feel less safe.

[58] During the 2016 legislative session, McComas opposed a bill to abolish the statute of limitations for child sexual abuse cases, saying that she was "skeptical it would do any good".