Ali Harbi Ali, 26, was also convicted of preparing acts of terrorism.
A 26-year-old man has been jailed for life after being found guilty of murdering Conservative MP Sir David Amess last October.
Ali Harbi Ali -- from North London -- was also found guilty of preparing acts of terrorism by the Old Bailey court on Monday.
On Wednesday, Judge Nigel Sweeney said he had "no doubt" about the need to impose a full life sentence on Ali.
Ali had stabbed Amess more than 20 times with a kitchen knife during a constituency surgery at a church in Leigh-on-Sea last year.
The 69-year-old MP for Southend West died at the scene.
Police had said Ali may have had a “motivation linked to Islamist extremism”.
Ali had denied the charges and told police he had targetted Amess over his vote for airstrikes on Syria.
"He also told detectives that he had researched other political figures as possible targets, with his planning stretching over a period of more than two years," the Metropolitan Police said in a statement.
"Detectives found evidence and CCTV footage showing that in 2019, he also visited the home address and the constituency surgery of two other MPs."
"Officers also found attack planning notes on his phone, as well as extremist content he had accessed."
The killing sent shockwaves across the United Kingdom and led to tributes from across Britain's political sphere.
UK Prime Minister Boris Johnson had stated that Southend will be given city status in tribute to Amess.
"A cowardly attack on a public servant doing his job is an attack on our country and our way of life," added the leader of the main opposition Labour party, Sir Keir Starmer.
The attack also came five years after Labour MP Joe Cox was fatally stabbed by a far-right extremist in her constituency, and has led to questions about the security of UK politicians.
“Sir David Amess was a dedicated public servant who was greatly respected and admired by everyone in his local community, and amongst his peers," said Detective Chief Superintendent Dominic Murphy, Head of Operations for the Met Police’s Counter Terrorism Command.
"His senseless murder shocked and appalled the nation," Murphy added.
"Sir David’s family have been left utterly devastated, but they have shown remarkable courage and dignity throughout the investigation and this trial."
"This senseless murder was a stark reminder that terrorism very much remains a threat."