He will spend at least seven and a half years behind bars after being sentenced on Monday.
The Hallam teenager wanted to advance violent jihad while striking fear into the public, Justice Michael Croucher said.
“That Mr Besim was planning such an outrageous and gruesome act of murder must terrify law enforcement officers across this country, their loved ones and right-thinking members of the community,” he said in the Victorian Supreme Court.
Besim discussed his plan in online chats with a UK teenager in March last year.
The UK boy’s arrest led to Australian authorities swooping on Besim on April 18.
The pair had been conversing about the 2015 terror plot “as if talking about something as ordinary as football tactics”.
Besim chose Anzac Day to “make sure the dogs remember this as well as their fallen heroes”.
“I’d love to take out some cops,” Besim wrote to the UK teen, who he thought was a married man with children.
“I was gonna meet with them then take some heads ahaha.”
Besim penned a suicide note, though some of his messages revealed “faint” suggestions he might have backed out.
He had been radicalised by older, influential extremists from the now defunct Al-Furqan Islamic Centre in Springvale, including senior IS recruiter Neil Prakash.
Besim was also greatly affected by the 2014 death of his friend Numan Haider and became alienated from society.
Besim was with Haider hours before the 18-year-old was shot dead outside Endeavour Hills police station after stabbing two counter-terrorism officers.
Besim wanted to travel overseas to fight with IS, but began plotting his Anzac Day scheme after being denied a passport.
He has engaged with moderate imams while in custody and says their guidance, plus months of reflection and reading, changed his radical views.
Justice Croucher wasn’t convinced Besim had renounced violent jihadist beliefs.
But he also said the teen’s youth, apparent contrition, guilty plea and lack of convictions made for good future prospects.
The 19-year-old pleaded guilty to one count of conspiring to do an act in preparation for or planning a terror act – a charge that carries a maximum sentence of life imprisonment.
He was handed a 10-year jail sentence and must serve at least seven and a half before he is eligible for parole.
The teen blew kisses to a large group of supporters as he was led away.
Police Minister Lisa Neville said the sentence was in line with police expectations.
“This is a case that actually really showed there was a real and imminent danger to our police officers,” she told reporters. “We can’t take these issues lightly.”