The candid conversation on Saturday included discussion of Dr Maté's impressions of Harry's memoir, which he said he initially "resisted" reading but was ultimately struck by "the universal humanity" of it.
Yahoo UK runs through some of the different reactions to the conversation, and why it's attracted so much attention.
Harry's drug use: 'Soaked in blood'
The Duke of Sussex and Dr. Maté talked candidly about the benefits — as they framed it — of using psychedelic drugs as well as the substances Harry used to cope with trauma in his younger years, like marijuana, alcohol and cocaine.
Harry said that cocaine "didn't do anything for [him], it was more a social thing", but that marijuana on the other hand was "different, that actually really did help me."
He also described taking the psychedelic drug Ayahuasca as "clearing of the windscreen", which removed the "filters" he saw life through.
The comments have attracted criticism.
Watch: Susanna Reid calls out Prince Harry over 'live therapy session'
Fiona Spargo-Mabbs, who founded the Daniel Spargo-Mabbs Foundation drugs education charity after her son died of an accidental MDMA overdose aged 16, described the comments as "concerning".
"Unfortunately young people are getting the message from somewhere that drugs are going to help with their problems and anything that reinforces that is a concern for us. Using drugs as a coping strategy is more likely to lead to dependence than other motivations because that becomes how you are coping with something."
Journalist and doctor Max Pemberton called Harry's comments "hugely irresponsible".
"He speaks about using drugs that are illegal in this country, proclaiming the benefits he has enjoyed from cannabis and hallucinogenics such as ayahuasca. It’s hugely irresponsible," he said
"Harry plainly has no understanding of the serious damage these substances can wreak on users - damage that I see on mental health hospital wards with upsetting frequency."
The outspoken television presenter Kirstie Allsopp was equally scathing, saying Harry's actions were "soaked in blood". She tweeted: "Someone needs to tell Prince Harry that County Lines doesn’t mean doing coke in the Home Counties. It means that stuff you took to ease your trauma, was soaked in the blood of those whose own trauma & lives are as far from your privileged bubble as it is possible to get."
'We should be empathising'
The reaction to Harry's chat with Maté wasn't all critical, with some praising the Duke of Sussex for his openness.
Barrister and academic Dr. Charlotte Proudman said people should be "empathising" rather than criticising Harry, saying: "We should be empathising with a man who bravely shares his battle with mental health not labelling him 'deluded' — this is dangerous and will discourage people from speaking out about trauma."
Omid Scobie — Yahoo UK's executive royal editor — called the talk with Dr Maté "powerful" on Twitter.
"Fascinating and powerful convo between Harry and Dr Gabor Maté and, gotta say, brave to do it live and so publicly. Maté didn’t tip-toe around the big topics or mince words and, as a result, provided one of the most revealing insights into Harry—who clearly knows his stuff—today."
Journalist Ellie Hall echoed Scobie's sentiments and added: "Harry has obviously done a lot of work on his mental health and feels comfortable enough in that work and in himself to be open and honest about his experience."
Cambridges get personal for Mental Health Minute broadcast: 'I'm Catherine. And I'm William' (Yahoo Life UK, 4 Min)
ADD Diagnosis: 'Neither ethical nor appropriate'
At one point during the conversation, Dr. Maté 'diagnosed' Harry with a series of mental health issues that the physician had identified in the duke whilst reading his memoir, this included Attention Deficit Disorder (ADD).
He said: "Reading the book I diagnose you with ADD, I see it as a normal response to normal stress, not a disease."
This comment that drew anger from the ADHD Foundation.
"Gabor Mate-it is neither ethical nor appropriate to tell someone for the first time,- in a public interview, that they have ADHD. It is for the individual to decide whether to disclose their Neurodiversity."
Joking about the diagnosis, Harry told Dr Maté: "Thanks for the free session."
ADHD: As Sam Thompson films TV documentary, what are signs and symptoms? (Yahoo Life UK, 7 min read)