His news entertainment show, Last Week Tonight, attracts a TV and online audience of millions each week.
It has become so influential on the subjects he tackles that it is known as the “John Oliver effect”.
The Emmy award-winning programme is about to start a fifth season, and so its host is giving interviews to promote it.
I started by asking him how he feels about the prominence of late night entertainment shows in the US right now.
He said: “I think that any time late night comedians are this prevalent in the national conversation, that’s probably not a great sign of national health.
“If there’s a canary in the coal mine it’s choking at that point.
“When late night shows are just a side show, generally things are going better.”
Oliver is no fan of President Trump, who is a frequent subject of the show.
One of his early rants about candidate Trump racked up nearly 34m views on YouTube alone.
Even though the avalanche of news around the current administration has been a fruitful topic, Oliver doesn’t seem that happy about it.
He said: “There is an abundance of material to a very real problematic extent. It is just a firehose of bulls**t.
“So the problem with that is when it’s coming at you that fast, it’s hard to filter out the stuff that means something, that means nothing, that you can ignore, that you must not ignore at all costs.
“It’s difficult to regain perspective when you’re just drowning all the time.”
Oliver said he thinks that Trump represents a genuine threat to America.
“He’s a fundamental threat to the institutions that this country is built on in a way that is not usually the case with a President on this scale.
“He is taking an axe to some pretty fundamental parts of American governance.
“What he’s doing with the State Department is going to have ramifications for years after he has gone.
“There’s a brain drain in government that is going to take generations to recover from.”
I pointed out that lots of people voted for him, and asked if he understood why.
He said: “There’s not one reason right, there are lots of reasons that people voted for him; some good, many bad.”
Brexit is also a favourite topic.
He said: “I would argue that there is nothing that’s not interesting about the British negotiations because that is a s**t show of the highest water.”
Does he think there should be a second referendum?
“Well, ideally, yes. Because it seems odd to make a decision based on information that was at best misleading, see the potential ramifications of that decision, and then be held to what may have been a misinformed choice.
“Now if people still want it, that’s fine.
“But I think if you still want it on the terms that are being presented to you that’s very different from wanting it on the terms that were presented to you on the side of a dumb red bus.”
He muses on the ever increasing traction of the term “fake news”, and how his own show has turned into a high stakes battle to maintain the trust of his audience.
He said: “We meticulously research the stories we are doing because we take some pretty big swings at politicians and corporations…if we get that wrong, it’s probably over for us, realistically.
“We can’t be fake because of the scary consequences that would come with being wrong, but also there is an extent to which if you build a story on sand it’s just going to collapse and you’ve demolished your own argument before anyone’s even attacked it.
“So (we) always have to make sure that the foundations of what we’re talking about are completely solid, otherwise we don’t really have anything to say.”
Will he give us a sneak preview of any emerging themes in the new season?
“If I told you the stories that we did last year ahead of us doing them, you wouldn’t watch because it would sound terrible, so like if I’d said to you last year, ‘we’re going to talk about vaccines for thirty minutes’, you wouldn’t watch because no-one wants to see that s**t.
“So part of the process of our show is selling to people in the moment, once we’ve already got your attention, why it’s worth listening to us talk about flood insurance for another 20 minutes.
“So yeah, the ingredients of our show are so objectively repulsive they don’t really work as a tease.”
Last Week Tonight airs on Sky Atlantic, Monday 19 Feb, at 10.10pm