Ali wore a black collarless robe and was flanked by three security guards as he arrived for his sentencing today.
Prosecutors described the case as “overwhelming”, and the 26-year-old Londoner himself did not dispute much of the evidence.
Ali was convicted on Monday of one count of murder, and one count of preparing terrorist acts.
He was handed a whole-life order at the Old Bailey today.
Far-right extremist Thomas Mair, who murdered Labour MP Jo Cox in 2016, is among the handful of prisoners in England and Wales subject to a whole-life order, while ex-Pc Wayne Couzens was also handed a whole-life term last year after raping and murdering Sarah Everard in south London.
Ali Harbi Ali
PA
Ali Harbi Ali in court
Elizabeth Cook
ISIS fanatic Ali carried out his attack at the backbench Conservative MP’s constituency surgery in Leigh-on-Sea, Essex, on October 15 last year.
Ali told the trial he had no regrets about the murder, defending his actions by saying Sir David deserved to die because he had voted in Parliament for air strikes on Syria in 2014 and 2015.
The court heard that Ali became known to authorities around this time as his school performance plunged and he was referred to the Government’s Prevent strategy, but continued plotting in secret.
The so-called “lone wolf” sent a manifesto on WhatsApp to family and friends seeking to justify his actions around the time of the attack, and told father-of-five Sir David he was “sorry” before plunging the 12in carving knife into him, causing the 69-year-old politician to scream.
Sir David received more than 20 stab injuries and died at the scene.
Knife-wielding Ali was later apprehended by two police officers armed only with batons and spray. They have since been handed bravery awards.
Sir David's aide Julie Cushion said in a statement: “Since October 15 last year I have to drive by the church where Sir David died nearly every day as it is close to where I live. This is a constant reminder of what happened.
“I have a huge sense of guilt as I booked the venue. I can never get (fellow staff member) Rebecca’s scream out of my mind as Sir David was attacked and if I hear someone scream now, I jump and imagine myself back there.
“I can still see and hear the sounds and images of the time, like the crashing of the furniture.
“I remember the feeling of distress while we waited for help, feeling helpless and hopeless as there was nothing I could physically do to help.”
Sir David's family said in a statement that they felt “no elation” after Ali was jailed.
The statement continues: “It breaks our heart to know that our husband and father would have greeted the murderer with a smile of friendship.”