Althea Garrison finally takes her seat on the Boston City Council

Althea Garrison was congratulated by Mayor Martin J. Walsh after she was sworn in as city councilor Wednesday. Josh Reynolds for The Boston Globe

If, at first, you don’t succeed, try, try, try, try, try, try, try, try, try, try, try, try, try again.

That may be the lesson of Althea Garrison’s unlikely return to elected office.

The indefatigable Dorchester resident has appeared on the Boston ballot no fewer than 32 times since at least 1982, as a Democrat, Republican, and independent perennially running for state representative, City Council, or mayor.

Only once — when her opponent failed to complete his nomination papers — has she won. That was back in 1992, when she served a single term as a Republican state representative.

Now, another political lightning bolt has vaulted the 78-year-old Trump supporter back into the halls of power, and she couldn’t be happier about it.

Mayor Martin J. Walsh on Wednesday swore in Garrison as Boston’s newest at-large city councilor, filling the vacancy created by Ayanna Pressley’s election to Congress in November.

City rules dictated that Garrison be given the $99,500-a-year job because she was the first runner-up in the last City Council election, when she finished a distant fifth, with just under 7 percent of the vote, behind Pressley, Michelle Wu, Michael F. Flaherty, and Annissa Essaibi-George.

During a brief ceremony in a packed City Council chamber, Garrison received warm applause from her colleagues and used her first speech to thank her backers who “kept the faith in my candidacy.”

She drew laughter and applause when she sent an implicit warning to the large field of candidates who are expected to try to replace her in the next City Council election this fall.

“For those of you who are wondering if I will be running for reelection, the answer is, yes, I will be running for reelection,” Garrison declared.

New City Councilor Althea Garrison smiled after taking her seat in the City Council chamber.Josh Reynolds for The Boston Globe

She comes to City Hall with an unusual backstory and political outlook.

Intensely private, she has reluctantly described growing up as the youngest of seven children in Hahira, Ga., a small town near the Florida border.

At 19, she moved to Boston to attend beauty school and graduated from Suffolk University with a degree in business administration. She recently retired after a 34-year career as a clerk in the state comptroller’s office.

Before serving as a state representative from 1993 to 1995, she was outed as transgender when the Boston Herald got hold of a birth certificate that listed her sex as male and her name as A.C.

Though regarded by LGBTQ advocates as the first known transgender person to serve in a legislature, she was mocked by the Herald for her physical appearance and has declined over the years to discuss her gender identity.

Now unenrolled in any party, she describes herself as a conservative and has said in the past that she opposes abortion, gun control, affirmative action, and same-sex marriage.

In her address on Wednesday, Garrison said she would fight for issues that many of her colleagues support — affordable housing, senior citizens, and homeless veterans.

Speaking to reporters, Walsh said Garrison will bring “continued diversity” to the 13-member council. He dismissed questions about her support for President Trump, noting that she wants to tackle the high cost of housing.

“The issues that are concerning to her are issues that are on the minds of most Bostonians,” the mayor said, adding that he’s talked to Garrison several times since Pressley’s election.

Althea Garrison waved to the City Council chamber. Josh Reynolds for The Boston Globe

Garrison’s supporters called her ascension to the council a moment of sweet vindication for a woman often dismissed as a political gadfly.

“It’s like a slap in the face to anybody that’s always talked badly about her,” said João DePina, a friend and community activist who owns his own floral design business.

DePina, who is 40 and identifies as bisexual, said he was troubled, however, that some continue to focus on Garrison’s gender identity, saying she doesn’t discuss it because she came of age long before transgender rights entered the political mainstream.

“I told her, ‘Don’t let the press and don’t let people make you have to worry about who you are as a person, and what you identify as, and what gender you are,’ ” DePina said. “ ‘Let’s focus on the work.’ And that’s what she’s doing, and I’m proud of her.”

Garrison said she is eager to begin her tenure on the council. She has hired a chief of staff and said she is looking for a constituent services director.

Wheeling a suitcase into her barren City Council office before the ceremony, an American flag pin affixed to her lapel, she said she was gratified but not surprised to find herself back in elected office after so many years of trying in vain.

“I never quit. I’m constantly running, and I knew it would pay off,” she said. “It pays not to quit when you want something. You have to keep working until you get it.”