He previously denied intending to kill the then presidential candidate in the 2024 incident
Routh (59) was convicted by a jury last September of five criminal counts, including attempted assassination, after serving as his own defence lawyer at trial. US district judge Aileen Cannon handed down the sentence in Fort Pierce, Florida.
“It’s clear to me that you engaged in a premeditated, calculated plot to take a human life,” Ms Cannon said.
Shackled at the hands and wearing beige prison clothing, Routh gave a rambling address at the sentencing hearing that did not touch on any facts of the case, but instead focused on foreign wars and his desire to be exchanged with political prisoners abroad.
Prosecutors had recommended a life sentence, while Routh had asked the judge, a Trump appointee, to impose a 27-year term.
Prosecutor John Shipley said during the hearing that Routh’s crimes were aimed at “upending American democracy” and urged Ms Cannon to send a message that political violence is unacceptable.

Ryan Routh served as his own lawyer during his trial last year. Photo: AP
Martin Roth, Routh’s lawyer, said during the hearing that Routh was a troubled and complex person, but that he had a “very good core” and cared deeply about the well-being of others.
Mr Roth told reporters after the hearing that he plans to appeal Routh’s conviction and sentence.
Routh in his remarks at the hearing called himself a “failure”, said his sentence was “totally unimportant” and lamented that “sadly, execution is not an option”.
“I have given every drop of who I am every day for the betterment of my community and this nation,” Routh said.
He read from 20 pages of prepared notes, but Ms Cannon cut him off after about 15 minutes, calling his remarks irrelevant to the case.
In an earlier court filing, Routh denied he intended to kill Mr Trump, and said he was willing to undergo psychological treatment for a personality disorder in prison.

Law enforcement officers arrest Ryan Routh after the 2024 incident. Photo: AP
He suggested jurors were misled about the facts of the case by his inability to mount a proper legal defence at trial.
Elsewhere, the Trump administration is reducing the number of immigration officers in Minnesota, but will continue the enforcement operation that has sparked weeks of tensions and deadly confrontations, border tsar Tom Homan said yesterday.
About 700 federal officers – roughly a quarter of the total deployed to Minnesota – will be withdrawn immediately after state and local officials agreed over the past week to co-operate by turning over arrested immigrants, Mr Homan said.

Ryan Routh has been sentenced to life in prison. Photo: AP
Today’s News in 90 – Thursday February 5
He did not provide a timeline for when the administration might end the operation, which has become a flashpoint in the debate over Mr Trump’s mass deportation efforts since the fatal shootings of US citizens Renee Good and Alex Pretti in Minneapolis.
About 2,000 officers will remain in the state after this week’s drawdown, Mr Homan said. That’s roughly the same number sent to Minnesota in early January when the surge ramped up, kicking off what the Department of Homeland Security called its “largest immigration enforcement operation ever”.
Since then, masked and heavily armed officers have been met by resistance from residents who are upset with their aggressive tactics.