Sarah Palin, a former Alaska governor and the Republican nominee for vice president in 2008, said Friday that she was entering the race for Alaska’s lone congressional seat, marking her return to national politics after she helped revive the anti-establishment rhetoric that has come to define the Republican Party.

She will be joining a crowded field of nearly 40 candidates to fill the House seat left vacant by Representative Don Young, whose unexpected death last month has spurred one of the largest political shifts in the state in 50 years.

Ms. Palin said she planned to honor Mr. Young’s legacy, painting a dystopian picture of the nation in crisis, criticizing the “radical left,” high gas prices, inflation and illegal immigration.

“America is at a tipping point,” she said in the statement. “As I’ve watched the far left destroy the country, I knew I had to step up and join the fight.”

In the past, Ms. Palin had suggested, but never followed through on, launching various campaigns for elected office several times in the years since she first electrified the base of the Republican Party after 2008 presidential nominee John McCain plucked her from obscurity and named her as his running mate.

But after a long hiatus from political life, Ms. Palin had hinted in recent weeks that she was more serious than she had been in the past about running for office again. In a recent appearance on Fox News with Sean Hannity, Ms. Palin said, “There is a time and a season for everything.”

And she invoked former President Donald J. Trump as an inspiration. The two had shared a stage in 2016 when she endorsed him for president. “We need people like Donald Trump, who has nothing to lose. Like me,” she said.

On the conservative cable network Newsmax, she did not rule out the possibility of running for Young’s seat last week, saying that she would consider it an honor. “If I were asked to serve in the House and take his place, I would be humbled and honored,” Ms. Palin told the network. “In a heartbeat, I would.”