A jury found that Ryan Routh, 59, intended to kill Trump, then a former US president and Republican presidential candidate, when he pointed a rifle through a fence while Trump was golfing at the Trump International Golf Club in West Palm Beach.
He was also found guilty on the four other charges he faced, including impeding a federal agent and weapons offences. He faces a maximum sentence of life in prison.
Routh appeared to try to stab himself with a pen several times after the verdict was revealed in court and had to be restrained by US marshals, according to US media reports. His daughter Sara also yelled in court that her father had not hurt anyone and she would get him out of prison.
Routh fled from the golf course without firing a shot after a US Secret Service agent patrolling the course ahead of Trump spotted Routh and the rifle and opened fire, according to witness testimony in the case.
"This plot was carefully crafted and deadly serious," prosecutor John Shipley said at the start of the trial, adding that without the intervention of the Secret Service agent, "Donald Trump would not be alive."
The 12-day trial in federal court in Fort Pierce, Florida, unfolded in the aftermath of the assassination of conservative activist Charlie Kirk, which again thrust the growth of political violence in the US to the centre of the national conversation.
Trump was targeted in two assassination attempts, including one that wounded him in the ear, during his 2024 presidential campaign that returned him to the White House.
"Today's guilty verdict against would-be Trump assassin Ryan Routh illustrates the Department of Justice's commitment to punishing those who engage in political violence," Bondi said in a statement on X.
"This attempted assassination was not only an attack on our President, but an affront to our very nation itself."
Trump, in a post on his Truth Social platform, lauded the verdict, adding, "This was an evil man with an evil intention, and they caught him."
Routh, who had pleaded not guilty to all charges, opted to fire his lawyers and defend himself at trial. His defence was based on what he described as his gentle and non-violent nature, but his meandering opening statement was cut off by a federal judge and he offered little pushback as a parade of law enforcement witnesses detailed the evidence in the case.
Prosecutors alleged that Routh arrived in South Florida about a month before the September 15, 2024, incident, staying at a truck stop and tracking Trump's movements and schedule. Routh allegedly carried six mobile phones and used fake names to conceal his identity.
He lay in wait for nearly 10 hours on the day of the incident, concealing himself in thick bushes overlooking the sixth hole green, prosecutors alleged.
Trump was on the fifth hole a few hundred yards away when Routh was discovered. Routh was arrested later that afternoon after being stopped by police along a Florida highway.
