The Somali-born rapper K’naan arrives at the K West, the west London hotel much loved by today’s rock stars looking half the part: hip-hop fly in his cardigan but also shy, fresh from shooting a video with the band Keane, prepping himself for a wearying flight out of Heathrow to Mozambique.

He is on the cusp of global recognition now that his song “Wavin’ Flag” has been chosen (by sponsors Coca-Cola) as the official anthem of this summer’s World Cup in South Africa.

It’s an uplifting song which “fits their theme of trying to see the positive in people, and the positive in Africa”, he says; but it’s a surprising choice, too, not simply because it demonstrates considerable good taste on the part of Coca-Cola, but because K’naan himself is not the most obvious poster boy for such an event.

It probably doesn’t matter that he’s not really the biggest football fan, although “we used to play in Mogadishu when I was little, and when the World Cup came around, we’d make up different teams in different neighbourhoods representing different countries and we’d wear the uniforms”.

I ask if the name John Terry rings any bells because the story of the Chelsea player’s infidelity is splashed over the front pages that morning, and he hasn’t a clue.

No, it’s more the fact that few rappers are quite so politically outspoken, with comments attributed to him about the pirates plying their trade off the Somali coast provoking headlines of their own.

“It’s always alarming for people to hear there could be another side to a story,” he says, arguing that for years, toxic waste has been dumped in Somali waters with the collusion of Western governments. This is view that he has also outlined in an article for the Huffington Post, describing “one man’s pirate [as] another man’s coastguard”.

When we meet, the story of the kidnapping of British couple Paul and Rachel Chandler from their yacht is still in the news, and he says “I do sincerely hope they’re safe and come home. This is an incredibly complex issue.”

K’naan – born Keinan Abdi Warsame – is no stranger to complexity himself.

With his mother, he was on one of the last flights out of Mogadishu as civil war engulfed Somalia in 1991 when he was 14.

The family lived first in New York, and a love of hip-hop and the fluid, visionary flow of rappers such as Nas helped K’naan through what he describes as post-traumatic stress disorder, giving him “some kind of release”: back home, after all, he had seen three of his friends shot dead. This marked him out from his peers.

“What we’d been through,” he tells me, “was a little harder than life in America’s ghettos. Watching people boast about what they were going through became a little boring, a little frustrating. When you don’t know there is something worse, more difficult, you tend to focus on your little pains and think ‘Ah, I have it so bad’. But you shouldn’t complain about a headache when someone beside you has a bullet wound.”

Of course, like any rapper, he fashioned his work from such observations.

One of his themes involves the true meaning of what is to be a “gangsta”.

“I take rappers on a field trip any day/They never been opposite real clip anyway,” he begins on T.I.A, the first cut on his ebullient current album, Troubadour. Elsewhere, he boasts that Mogadishu is “the only place worse than Kandahar”.

“I don’t feel political most of the time,” he says softly. “Sometimes I’m placed in positions because no one else will go there. I understand that, and I owe it to the people I live among to explain any misunderstandings about the place I come from.”

From New York he moved to Toronto, forging a career on the Canadian hip-hop scene.

A Muslim who had committed the entire Koran to memory by the age of 11 – and who knows, perhaps that also informed his love of words? – he admits “sometimes I make all the mistakes”.

But an intensity drove him on. “I jokingly say to my friends sometimes, I wish I did drugs, because they seem so chilled!”

His trip to Mozambique is to finish recording a new video for “Wavin’ Flag”; he recently visited the same country as part of Coca-Cola’s Trophy Tour with the World Cup, a pan-global publicity jaunt which touched down in 18 African countries in the course of 22 days.

Bearing in mind incidents such as the attack of the Togo team during the recent African Cup of Nations, is an African nation ready to host such a major tournament?

“You can’t tell people to stay away from the continent because of what happens in one country,” he says. “Besides, we are all complicit in the problems – and we all have to contribute to the positivity.”

I assume that tour of Africa couldn’t possibly include a visit to Somalia, and that he has never returned since fleeing the country as a teenager.

“I went,” he says disarmingly, “for three weeks in December. On my own. I didn’t tell anybody I was going. It was the worst heartache my mom’s ever known.” Several members of K’naan’s family still live in Mogadishu, but “they’re trapped there: the city is a war zone”.

He went instead to Hargeysa in the north of the country, and visited friends and extended members of the family.

Was it dangerous? “Well, walking around with a pistol is a pretty strange sensation. And there was a bomb placed in the road for our party at one point, but we figured it out.”

More than anything, the trip confirmed K’naan’s instincts.

“I always thought of Somalis as being creative people – very musical, artistic, poetic – and as active people. And I saw that. They’re not waiting for some kind of saviour. They’re getting on with their lives.”

Everywhere he went, it seemed, people knew of his success abroad.

“I’d walk through a market, and the entire place would be lined with people wanting to shake your hand to say thank you for what you’re doing. They get that I’m there for them – and in a sense, my success is their success.”

K’naan is 31 and reaching a far wider audience than he ever imagined possible.

The video he’s been making with Keane marks his appearance as a guest on their new EP (“He’s just ultra cool,” says their singer Tom Chaplin. “Very down to earth, as well as being just an incredible wordsmith.”); recently, Jay-Z came to one of his concerts, and later emailed to say of “Wavin’ Flag”, “Congratulations, you just made an anthem for a generation.”

Nonetheless, there is still a huge vulnerability to him. “I’m an optimist about other people,” he says to me at one point. “I’m not an optimist about myself. Before I went to Somalia last year I didn’t know if I could write another album.

“I went completely uncertain that I would return,” he continues. “I really did throw in my hat, and say ‘if it’s ever time to go, this is the best time’. And I mean ‘go’ in many ways. But I was so in the arms of people. I’d check my email once in a while and say ‘Hey Mom, I’m alive. And you know what? It’s amazing here!’ It gave me a second life.”

It was finally time for K’naan to move on.

“I needed to be freed from my childhood,” he says. “Without going home I couldn’t do that. My question about my art and my music has always been ‘am I good or am I good because?’ I’m not the artist who wants to have the because attached.”